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By A. H. Daane, W. J. Wunderlin, B. J. Beaudry

The solid solubility of holmium in copper, silver, and gold, determined using metallographic techniques, was found to be a maximum of 0.06, 2.4, and 3.2 wt pct, respectively, nt the eutectic temperatures. The temperatures of these eutectic horizontals, determined by differential thermal analysis, were found to be 868", 787", and 778"C, respectively. The first compound on the silver-rich side of the Ag-Ho system was found to be A&Ho2. In a study by Gold et al.,' on the effect of small amounts of soluble impurities on the electrical resistance and thermoelectrical properties of copper, traces of iron were shown to have drastic effects on the thermoelectric power due to the magnetic scattering of the conduction electrons. Since little is known about the state of the iron ion when dissolved in copper, Gold had hoped to repeat these experiments using certain rare earths as the magnetic scattering centers; because of the tightly bound 4f electrons it is not expected that their spectroscopic state would be affected by alloying. In such an experiment the sole role of the trace rare-earth impurity would be to magnetically scatter the copper conduction electrons without producing appreciable distortions in the otherwise pure copper matrix. Since holmium was chosen for such a study because of its high magnetic moment, it was necessary to establish precisely its solid solubility in copper. The study was extended to include the solvents silver and gold, so that an evaluation of the data using classical solubility parameters could be made. No previously reported work on the systems of holmium with copper, silver, or gold was found in the literature. Information on the solubility of other rare earths in these three metals is also very meager. The solubility limit of yttrium in copper was reported as less than 1 wt pct2 and the solubility of praseodymium in gold as 0.35 wt pct,3 while no references were found on solubility studies of rare earths in silver. EXPERIMENTAL Materials. The materials used in this investigation were distilled holmium prepared in this Laboratory, OFHC* copper, electrorefined silver (99.9 *OFHC = oxygen-free high conductivity. pct), and gold with the analyses given in Table I. Sample Preparation. Samples weighing 1 to 2 g were prepared by arc-melting the components together on a water-cooled copper plate under purified argon atmosphere. The samples, turned and remelted at least five times to ensure homogeneity, showed weight changes of less than 0.1 wt pct after melting. Samples containing less than 0.7 wt pct Ho were prepared by diluting 1 to 2 wt pct Ho alloys with the pure solvent, while samples with concentrations greater than 0.7 wt pct Ho were prepared directly from the metals. The samples were wrapped in tantalum foil, sealed in outgassed Vycor tubing under helium, annealed at the desired temperature for at least 24 hr, and then quenched by shattering the Vycor tube in cold water. Metallographic Methods. Standard mechanical polishing methods were used in preparing the silver and gold alloys for examination, while the copper alloys were electropolished using a 40 pct solution

Jan 1, 1963

By S. F. Reiter, W. R. Hibbard

A survey of the effect of heat treatment on the room temperature hardness of Fe-Mo alloys has been made. Constant strain rate tensile tests were performed between room temperature and 1800°F. These data were analyzed to determine the effect of temperature and composition on the strain hardening coefficient and strain rate sensitivity. Constant load creep-rupture tests were made on these alloys and the results related to composition and structure. A relation between the high temperature strength of the precipitation hardened alloys and the volume of precipitate has been observed. IN view of the extensive use of ferritic materials at elevated temperatures, it is surprising to note the limited amount of information relating the variables of plastic deformation, i.e., composition, structure, temperature, stress, strain, and strain rate. Hollomon and Lubahn' showed how the several variables of plastic flow might be treated analytically. No data were available on carbon-free iron and its alloys in a form suitable for this analysis. Several German investigations2-" constitute most of the experimental work relating high temperature properties to the constitution of these types of materials. In order to obtain new data, the iron-rich alloys of the Fe-Mo system were selected for detailed investigation for the following reasons: 1—Some of the important effects of molybdenum on the mechanical properties of iron have already been studied.' , 821 2—By suitable heat treatment of selected alloys, it is possible to study strengthening effects of four types: AT -a transformation, B—substitutional, C—precipitation, and D—dispersion of hard inter-metallic compound. Materials and Treatment Four-pound ingots were vacuum cast, employing the same melting schedule previously used.? The raw materials were electrolytic iron and lamp-grade molybdenum. The ingots were forged to l/z in. sq. rod and one portion swaged to 0.350 in. diam rod for the production of 1 15/16 in. long button-head specimens. The button-head specimen blanks were solution treated for 16 hr at 2100°F in hydrogen of —70°C dewpoint and then water quenched. They were subsequently plunge ground to the standard 0.160 in. diam test bar. Micrographs of the solution treated alloys are given in Figs. la through Id. The higher molybdenum alloys contained large equiaxed ferrite crystals similar to those in Fig. Id. A portion of the % in. rod was hot rolled to 0.100 in., sandblasted, and cold rolled to 0.020 in. Strip tensile specimens having a 0.020x0.200 in. cross-section and a 2.25 in. gage length were machined from the sheet. The alloys containing molybdenum were subsequently annealed 1 hr at 1560°F. The iron strip was annealed 4 hr at 1300°F in wet hydrogen. The resultant structures are shown in Fig. 2a through h. The ASTM grain sizes were 1 to 3 as solution heat treated or 3 to 4 as annealed. The chemical analyses of the alloys are given in Table I. Carbon contents were obtained after the heat treatments in hydrogen. Alloy 15.9 pct Mo was tested as a cast alloy.'

Jan 1, 1956

By R. V. Smith, E. J. Dewees, R. H. Williams

Before this paper was presented, the terms "f" and "v1/f in flow equations had been called "friction coefficient" and "friction factor," respectively. However, many authors have used the names for the terms interchangeably, with the result that considerable confusion has existed in the literature on flow of fluids. In an effort to establish a clear and concise terminology for these terms, the authors have designated f as "resistance coefficient" and dm as "transmission factor." Transmission factors for the flow strings of gas wells were determined by tests on wells in six fields of Oklahoma, Texas, and Louisiana. Data were collected on 14 gas wells while gas was flowing through 1 1/4, 2, 21/2, and 3-in. tubing and 51/2 and 7-in. casing. The transmission factors developed from these data were found to follow the resistance equation published by Nikuradse1 for turbulent flow in "rough" pipes with an average absolute roughness of 0.000,65 in. This average absolute roughness is believed to be representative generally of the flow strings of gas wells with the exception of those that have been exposed to corrosion or other conditions causing undue roughness. Also, use of an absolute roughness of 0.000,65 in. probably will result in transmission factors that are more representative of gas-well conditions than those in common use today, provided that the transmission factors are calculated by the methods outlined in this report. The authors believe that use of these transmission factors will permit calculation of more accurate subsurface pressures in gas wells than those in use today. Engineers use transmission factors in flow equations to compute subsurface pressures in flowing gas wells from measured wellhead pressures. These subsurface pressures are necessary for determining the productivity of gas wells from "back-pressure" tests. The methods of calculating pressures in flowing gas wells, as outlined by Rawlins and Schellhardt2 in Bureau of Mines Monograph 7, are based on the transmission factors in the well-known Weymouth formula" Natural gas engineers have realized that errors introduced by using transmission factors as given by the Weymouth formula are relatively unimportant in testing low-capacity gas wells; but they also know that such factors are important considerations in testing large-capacity wells. Accordingly, the research described in this report was undertaken to fulfill the need for more accurate means of calculating subsurface pressures in gas wells. This report is part of the Bureau's study of the flow of natural gas through pipe and commercial pipelines. Several of the conclusions regarding flow in the flow strings of gas wells were influenced by the results of the study of flow in horizontal pipelines. These instances are mentioned in the text of this report. METHODS OF COMPUTING TRANSMISSION FACTORS Methods and procedures for computing transmission factors for turbulent flow in circular pipes from test data taken on gas wells have been derived and explained in detail in a paper by Smith4. As these methods were used to calculate the transmission factors presented in this report, a summary is included. Starting with

Jan 1, 1955

By J. D. Cooner

Since my working life of 32 yr has been spent in and about the anthracite mines of the Hudson Coal Co., and the previous 4 yr in a college school of mines, I can write best about the safety program of a coal mining company. However, most of the suggestions, statements and practices mentioned herein are applicable to the members of a safety organization and program of almost any industry. It is realized that industrial officials actually interested in real safety work are fully acquainted with the requirements of a practical safety program. Therefore, for such persons there may be nothing new in this paper. The Hudson Coal Co. of Scranton, Pa., employs 7000 men and produces 5,000,000 tons of anthracite annually at nine collieries scattered for a distance of 40 miles throughout the Lackawanna and Wyoming valleys of northeastern Pennsylvania. For the past 17 yr of the above mentioned 32, I have been engaged in safety work as a safety inspector, assistant mine superintendent, and at present the safety engineer. I have also had the privilege of visiting coal and metal mines in other parts of the United States and Canada. We Americans are the most careless people in the world. If any one doubts this statement why are 100,000 of our people killed accidentally annually? Or why during the almost four years we were engaged in World War II were more of our people killed accidentally at home than were killed in our army, navy, marine corps, coast guard, and other services during the same period? We are careless everywhere— in our homes, on the highway, at work and at play. The purpose of this paper is to outline the requisites of a safety department and its program to stop the accidents occurring to employees at work in mines or industrial plants. The first requisite for a safety program is that the management must be convinced of the need and value of a real safety program. By "management" is meant each department head from the president down. Otherwise a good safety department with a good safety program will not succeed because it will not have the proper personnel and equipment to work with, its rules and regulations will not be enforced, and the members of the safety department will be belittled in the eyes of most of the workmen and supervisors. Next, a safety engineer and his inspectors should have worked in the production end of the mines as workmen and also in an official capacity. They are then in a position to have practical and first hand knowledge of the accident hazards of the industry, how to prevent them, and in general the problems of both the workmen and officials. Some men are appointed as safety inspectors when they are physically unable to carry on as mine officials. Such men may know the safety end of the industry and even be safety-conscious, but if they are physically unable to be mine officials they are also physically unable to be safety inspectors, as a safety inspector in our mines must walk from 2 to 4 miles on each daily inspection and visit each working

Jan 1, 1949

By C. A. Bruch, J. F. Duffey

On the basis of metallographic and cooling-rate studies of 15 U-Zr alloys, a new version of the 6 phase region of the U-Zr phase diagram is proposed. IN several published diagrams of U-Zr alloy system:' there is good agreement that at elevated temperatures complete solid solubility exists between y uranium and ß zirconium. Similarly, there is reasonably good agreement concerning the uranium-rich and zirconium-rich ends of the diagram. However, there is no agreement concerning the nature of the diagram at intermediate compositions and at temperatures below about 650°C. The early work of Saller et al.8 hows an intermediate phase, 6. In a later diagram by Saller and Rough' shown in Fig. 1, the d phase field is drawn with dotted lines, indicating doubt that this phase exists. The diagram of Summers-Smith2 does not show the d phase. More recently Holden and Seymour' have shown that in the composition range 40 to 60 wt pet Zr, the high-temperature ? phase, which is body-cen-tered-cubic, transforms to an ordered structure, 8. They found that the order-disorder transformation occurs between 595° and 610°C, and presented a diagram based on the study of four different alloy compositions. Most recently Saller et a1.5 presented a new diagram which differs with respect to the composition limits of the 8 field from the others proposed by these authors. The purpose of the present investigation was to determine the boundaries of the d phase field. Experimental Procedures and Results Alloys—Buttons, weighing 80 g of 15 different alloy compositions were prepared by arc melting Mal-linckrodt uranium and iodide-process zirconium in a water-cooled crucible. A controlled atmosphere of argon and helium was maintained in the furnace. Prior to making each button, a sacrificial button of zirconium was melted to increase the purity of the furnace atmosphere. Each alloy was then melted six times to improve its homogeneity. Subsequently the alloy buttons were jacketed in copper and hot rolled to slabs at 775°C. From these slabs, specimens were machined for chemical, thermal, and metallographic analyses, Table I gives both the estimated chemical composition of the alloys, and the values which were obtained by analysis. The oxygen contents varied from 0.013 to 0.032 pet, nitrogen from 0.0014 to 0.014 pet, and carbon from 0.0013 to 0.011 pet. The purity of the alloys ranged from 99.947 to 99.975 pet. Thermal Analysis—The specimens for thermal analysis were blocks 11/4 x 1/4 x % in. The bead of a calibrated thermocouple was placed between two of these blocks and molybdenum wire was wrapped around the assembly. Each assembly was sealed in a quartz capsule having an argon atmosphere. The capsule was placed inside a refractory crucible which was heated in a furnace. Using a method described by Smith,' the emf of a differential thermocouple, with junctions inside and outside of the refractory crucible, was used to activate the

Jan 1, 1959

By Irving Cadoff, Richard Nolder

An analysis oj a series of samples of single -crystal silicon grown on sapphire shows that ,four distinct orientation relations exist. There are at least thirteen crystallographic planes which serve as substrates ,for epitaxial growth The model which assumes that silicon substitutes for aluminium and bonds with the oxygen atoms of the sapphire to form the first later for subsequent growth can account for the epitaxial geometry in all four cases. Multiplici-ties 01 specific orientations are found which are explained by the symmetry of both the sapphire and silicon crystal structures. It was reported in the previous paper' that single-crystal silicon films can be deposited on single-crystal a A1,03 (sapphire) with a wide variety of orientations. The silicon films, however, were found to deposit in only four different orientation relationships with respect to the sapphire substrate. The X-ray data have been analyzed to determine the plane and direction of atomic fit and an atomic model to account for the epitaxial relationships at the silicon-sapphire interface has been developed. These results are described in the present paper. EXPERIMENTAL The Laue X-ray data described in the previous paper were reduced to stereographic projections in a standard manner. These data were supplemented with X-ray reflection data obtained with -& E and A Full-Circle Goniometer (Electronics and Alloys, Inc.) mounted on a Phillips diffractometer unit. The silicon films were thin enough to result in characteristic reflections from the substrate as well as the silicon. The superimposed stereographic projections were analyzed to determine the orientation relationships. Ambiguities were resolved by referring to constructed models of various lattice planes for both silicon and sapphire. These lattice models were also used to develop the model for atom fit at the interface. DATA AND ANALYSIS 1) Crystal Structures. The crystallography of silico-n, which is of the diamond cubic class with a. = 5.4~, is straightforward. The sapphire structure is more complex and generally difficult to represent in pictorial form. It is of the rhombohedra1 class but usually referred to hexagonal axes. The transformation of indices between these two systems can lead to ambiguities which will have bearing on the analysis presented herein. Therefore, the basis used in this paper is described in the appendix. Referred to the hexagonal system, the parameters of sapphire are co = 12.95.&, a, = 4.75~, c/a = 2.73. All parameters are for room temperature. Figs. 1 and 2 illustrate schematically the hexagonal unit cell model of sapphire used for this analysis. The oxygen atoms are assumed to occupy positions in an idealized hexagonal array on basal planes. Their actual positions are in a slightly distorted hexagonal array. The aluminum-atom positions are scaled to their actual positions in the lattice with respect to the basal layers of oxygen atoms. It was found that an idealized model where the aluminum atoms are assumed to lie exactly at the octahedral interstices of the oxygen lattice, similar to that used by ~ronberg,' was not adequate for this study.

Jan 1, 1965

By D. Havlena, A. S. Odeh

The use of the straight-line method of solving the material balance equation is illustrated by means of six field cases. Also, the application of statistical criteria to arrive at the most probable answer is shown. The theory underlying the straight-line method of solution and the applicability of the statistical criteria was presented in a previous paper.' The field cases include saturated and undersaturated oil reservoirs with and without water drive. The aquifers discussed are: limited radial, infinite radial, very small aquifer and infinite linear. The field cases also include a gas reservoir producing under water drive. INTRODUCTION In a previous paper,' the authors presented the theory underlying the solution of the material balance as an equation of a straight line. The appropriate equations for various material balance cases as well as the methods of analysis and interpretation with comments and discussion were also included. To illustrate the various theoretical cases treated previously, five field cases are analyzed in this paper by employing the straight-line method of solving the material balance equation (MBE) and one example previously published is referred to. The use of statistical criteria to arrive at the most probable answer is also shown. All the field examples presented, except Case 2, are excerpts from complete reservoir studies. To illustrate the method, only sections specifically dealing with the material balance principles are included. Additional geologic information and basic data are reported to better acquire an understanding of the cases and thus to better follow the reasoning that suggested the successful application of the straight-line method of solving the MBE. The six cases are: (1) saturated reservoir, small gas cap, limited aquifer; (2) saturated reservoir, very small gas cap, infinite aquifer; (3) undersaturated-saturated reservoir, very small aquifer; (4) highly undersaturated reservoir, no water drive; (5) high undersaturated one-well reservoir, limited aquifer; and (6) gas reservoir, infinite linear aquifer. THE D4 SAND, GUICO FIELD, VENEZUELA The D, sand, which was discovered in 1943, is presently in a depleted state. Since its discovery it has produced under water drive, gas-cap-gas expansion, and solution gas drive. In Nov., 1947, water injection was initiated to arrest further pressure decline. When discovered, the D, sand was a saturated reservoir with a gas cap /oil zone volume ratio m estimated volu-metrically at 0.0731, an average permeability of 500 md, a porosity value of 25 per cent, and an oil viscosity at reservoir conditions of 0.3 cp. The volumetrically determined stock-tank oil initially in place was 23.1 million bbl. The volumetrically weighted physical data and production data available until Nov., 1953 are reported in Table 1. In Ref. 1, the effects on the straight-line plot of various values of ro/r for a constant ?to, or of various dimen-sionless times for a constant r8/r10 were theorized and were illustrated in Fig. 3A of that reference. In this field case, the previously theoretically predicted effects are established. Thus, the MBE calculations using Eq. 3c of Ref. 1 were performed for various r6/r10 and dimension-less time values. Eq. 3c of Ref. 1 is:

Jan 1, 1965

By C. D. Rubert, W. J. Parton

A flotation plant was placed in operation in 1945 at the Tamaqua colliery of the Lehigh Navigation Coal Co. Inc., to recover fine anthracite which is discharged from the cleaning plant with the washery water.‡ In addition to the recovery plant, facilities were provided for the complete clarification of the washery water, recirculation of this clarified water for breaker use, and disposal of the refuse solids in a waste impounding dam. Fig I shows a view of the settling tanks and the flotation plant. Flow Diagram The flow diagram for the complete recovery project is given in Fig 2. All the waste water from the cleaning plant is collected in a sump A outside the breaker structure, from which a 7000 gpm pump B delivers it through a 16 in. line to a 75-ft diam hydroseparator C. The hydroseparator, acting as a classifier, is set to give a separation at approximately 200-mesh. The minus 200-mesh overflow is discharged by gravity into the 180-ft thickener D for final settling of the solids. The classifier underflow sludge is pumped to the flotation plant by a 6-in. quadruplex diaphragm pump E. A 10-ft diam hydroseparator F is used to make a second classification on the sludge solids at approximately 28-mesh. The underflow from this classifier containing the coarse particles is elevated by a 6-in. diaphragm pump G and is discharged on two 4- by 6-ft vibrating screens II. These screens are dressed with approximately 28-mesh cloth. Screen oversize product flows directly to the centrifuge that dewaters the cleaned froth. The screen underflow and the overflow from the 10-ft classifier flow to the flotation circuit. The flotation feed is conditioned in a 12 by 12-ft agitator tank J at a pulp density of I:2.33 (30 pct solids). Reagents are fed to the circuit by reagent feeder I. The conditioned pulp is then diluted to a pulp density of approximately I: 5 (18 pct solids) and is fed to two banks of four 100-cu ft froth flotation cells K for primary coal recovery and cleaning. Additional reagents from reagent distributor L are added to the feed weir-box of Nos. 2, 3, and 4 cells of each bank of flotation machines. Clean coal removed from these cells flows directly to the clean-coal sump. Dilute tailings from the primary cells is re-thickened in a 30-ft diam thickener M and is then retreated in a scavenger circuit for final recovery of coal. The scavenger circuit consists of a 6- by 6-ft agitator tank N and two banks of four 24-cu ft froth flotation cells 0. Coal froth from these cells flows to the dewatering equipment and the tailings flows to a vertical refuse pump which delivers it to the 180-ft diam waste thickener D. Dewatering of the coal products is accomplished in a 54- by 72-in Bird centrifugal filter P. The cake product is dropped onto a conveyor and is loaded

Jan 1, 1949

By R. M. Brick, J. T. Richards

Tests have been conducted to determine the mechanical properties of several beryllium copper alloys down to liquid air temperatures. The materials investigated include beryllium copper, beryl-lium-cobalt-copper, and beryllium-zinc-copper in the wrought and cast conditions. As a means of evaluation, the influence of cold work and age hardening treatment upon subzero behavior has been observed. The effects of temperature upon both elastic and plastic deformation are also considered. THE low temperature mechanical properties of beryllium copper are of current interest in view of the increasing number of subzero applications. At extremely low temperatures, beryllium copper components are employed in temperature control and gas liquefaction equipment. At more moderate temperatures, such as those encountered in arctic regions, these alloys find use in a wide range of civilian and military applications. Although several previous subzero investigations have included beryllium copper,'-' none have been complete with respect to test temperatures or materials employed. As indicated in Table I, the alloy: used by Colbeck and MacGillivray,1 Walle,2 and Kostenets' were nonstandard and were not representative of present commercial practice. In addition, Kostenets4 did not test age hardened specimens, while the temperature in the other investigations", "-' were not carried below —100°F. These tests, however, indicate that beryllium copper offers interesting possibilities in subzero atmospheres, since the increase in strength with decreasing temperature is not accompanied by a reduction in ductility or impact resistance. As a means of checking and extending this earlier work at subzero temperatures, an investigation was undertaken at the University of Pennsylvania. In addition to testing the standard 2 pct beryllium copper, other alloys were also considered in wrought and cast forms. Charpy impact and tension tests were included with particular emphasis on the elastic characteristics, since beryllium copper is frequently selected for its spring qualities. Nominal test temperatures were +80°, —75", —200°, and —300°F. Test Materials Wrought beryllium copper, beryllium-cobalt-copper, and beryllium-zinc-copper specimens were machined from 0.560 in. diameter rod. These alloys were tested in the solution treated, cold drawn, or age hardened conditions. In the case of solution treated beryllium copper, some specimens were aged (3 hr at 600°F) for maximum hardness and others were overaged (1 1/2 hr at 750°F) to determine the effect of heat treatment. The compositions and average room temperature properties of these wrought alloys are presented in Table 11. The casting alloy versions of beryllium copper and beryllium-cobalt-copper were prepared as sand-cast cylinders, roughly 3/4 in. diameter x 6 in. long. Test specimens were machined from these cylinders. Conditions tested included as cast as well as solution treated and age hardened. Table 111 lists compositional and room temperature property data for the cast alloys. Test Methods Tension tests were conducted on specimens having a 0.25 in. diameter reduced section over a 1 in. gage length. To insure axiality, specimens were loaded by means of hardened chains. The yield strength at 0.2 pct offset was obtained from autographically recorded stress-strain curves resulting from a spe-

Jan 1, 1955

By William H. Spice

Exploratory drilling in South Central Texas for the year 1944 showed a marked increase over that of 1943 and resulted in a similar increase in new fields discovered. In this area, which comprises the 30 counties included in district No. I, Oil and Gas Division, Railroad Commission of Texas,? 61 exploratory wells were drilled during 1944 as compared with 29 exploratory wells drilled during 1943, or an increase of over 100 per cent. Three new oil fields, two new gas fields and one gas-distillate field were discovered during the year, as compared with one new oil field and one new gas field discovered during 1943. These new fields were the result of exploratory drilling throughout the district along the Wilcox trend and the deeper Edwards lime trend, which was started during the previous year. The Wilcox trend yielded the new Loma iilta-Wilcox oil field and the San Caja gas-* tlistillate field, both in McMullen County. The Charlotte field, in Atascosa County, was discovered along the deeper Edwards lime trend. These three discoveries were of considerable importance and subsequent development should indicate the desirability of continued exploration along these trends. The other three discoveries, United oil field in Guadalupe County, Pederson gas field in Milam County and Van Cleve gas field in Zavalla County, were of minor importance. Charlotte Field, Atascosa County, was discovered by the Humble Oil and Refining Company's No. 3 Pruitt, completcd on Aug. 9, 1944, flowing 176 bbl. per day, 3/16-in. choke, 710 lb. tubing, 475 lb. casing pressures, 37.7º A.P.I. gravity, from the top of the Edwards lime from 6917 to 6923 ft. Two oil wells were completed during the year in this field. This discovery is 14 miles southwest of the same company's Imogene field, also producing from the Edwards lime but with considerable difference in reservoir characteristics. The discovery of this field is the result of surface geology and subsequent seismograph survey of the area. Loma Alta-Wilcox Field, McMullen County, was discovered by the Atlantic Refining Company's No. I Atkinson, completed on June I, 1944, flowing 102 bbl. per day, 9/64-in. choke, 1900 lb. tubing pressure, 37º A.P.I. gravity, from Wilcox sand from 6866 to 6869 ft. after being drilled to a total depth of 7185 ft. This discovery is the result of subsurface geology and an extensive seismograph survey of the entire area. Sun Caja Field, McMullen County, was discovered by Edwin M. Jones No. 2-C Ezzell, completed on June 2, 1944 as a dual completion in the Wilcox sands, flowing 1,740,000 cu. ft. gas with 53 bbl. distillate, 1/4-in. choke, 2035 lb. tubing pressure, 53.2º A.P.I. gravity, from sand 6416 to 6453 ft. and flowing 2,000,000 cu. ft. of gas with 127 bbl. distillate, 1/4-in. choke, 2500 lb. tubing pressure, 50º A.P.I. gravity, from sand 6889 to 6916 ft., after being drilled to a total depth of 7264 ft. Three gas-distillate wells were completed during

Jan 1, 1945

By W. E. Anderson, T. M. Brady

As part of a larger study to identify factors influencing the practical operating life of wire rope used on large draglines in surface coal mining, field trips to operating surface coal mines were made during late 1975. Wire rope performance information was obtained from personnel at 13 mine sites west of the Appalachians. Seventeen pieces of equipment, utilizing bucket sizes ranging from 30 to 220 cu yd (23 to 168 m), were documented. Draglines at large US surface coal mines can be represented as 120 machines having 60-cu yd (46-m3) buckets, moving 1.8 X 109 cu yd (1.4 x 109 m3) of overburden during 6650 hours of productive availability per year. Based on the limited field study, the calculated downtime resulting from rope-related causes averages 105.6 hours per year for each typical 60-cu yd (43-m3) dragline. The total loss in production from this source alone is thereby estimated at about 25 x 106 cu yd (19 x 106 m3) annually. Although study findings did not reveal anything about dragline rope life that wasn't known or practiced by one operator or another, most operators can expect improved rope life by periodic review of their practices and by adopting one or more life-improvement measures employed at other sites. Since rope productivity was found to vary by a factor of five among the sites studied, considerable improved average performance is possible. As little as 10% overall improvement would increase national productivity by 2 million cu yd (1.5 X 106 m3) of solid overburden removal. Associated savings in rope costs would be some $2 million annually, plus a large reduction of labor-related expenses. This report outlines preliminary findings which may prove useful to many operators in extending wire rope life. Some of these modifications or adjustments in maintenance/operating practices would not require capital investment. During the field survey, no company was found which had tried cost reductions by using presocketed dump ropes, or dump rope sheaves that opened like a snatch block, so these are suggested as possible improvements requiring modest capital input. Data Acquisition During the field visits, mine operators provided rope life information about their machines. Some of the rope life data consisted of gross averages; other data was in the form of detailed records, including rope construction and manufacturer, cutoff and resocketing periods, end-for-end switching, and downtime for rope change-out. Trends of average hoist rope life and average drag rope life determined from the field study are shown in [Fig. 1] as a function of bucket size. The three lines on the graph have slopes of 1, M, and 1/4. A comparison of the data shows that hoist ropes moved about twice as much material as drag ropes prior to retirement, although more than a two-to-one scatter within each category is evident. As expected, the larger machines with the larger buckets moved more total volume of material. The four pairs of solid symbols represent those data for which detailed rope life histories are presented in subsequent figures.

Jan 1, 1980

By T. K. Prentice

ABSTRACTED AND REVIEWED BY E. W. DAVIS,* MEMBER A.I.M.E. THE January-February number of the Journal of the Chemical Metallurgical and Mining Society of South Africa is made up entirely of a discussion of Ball Wear in Cylindrical Mills. Following the principal paper by T. K. Prentice are several remarkably pertinent and carefully prepared discussions. Few persons in this country would be likely to see this publication, and since the information presented is new and of current interest, it seems desirable to abstract and review this publication for the benefit of the members of the A.I.M.E. The purpose of the investigation is stated in the first two paragraphs of Prentice's paper, as follows: Early in 1941, The Chamber of Mines Steel Products, Limited, initiated a series of tests under semi-working scale conditions to determine, if possible, those physical and chemical properties of a ball which make it resistant to wear when used in a cylindrical mill as a grinding medium, with the primary object of incorporating those beneficial qualities in the balls being produced at their works. This paper describes the tests carried out and discusses the results obtained. From these results it was possible to formulate a new theory relating to ball wear in cylindrical mills. This theory is presented in the second portion of this paper. PRACTICAL BALL-MILL TESTS IN A CYLINDRICAL MILL Part I of the paper begins with a discussion of the methods used for the manufacture of grinding balls in South Africa. The following paragraph is of particular interest. The cast steel ingots, 4 ¼ - in. square by 3 ft. 6 in. long, are re-heated in a gas-fired sloping stationary-hearth furnace and then rolled in a six-pass continuous mill into 2 5/8 in. round billets. Some of these billets are then removed and cut into suitable lengths for forging into 4 in., 3 ½ in., 3 in. or 2 ½ in. balls by means of three Drop and two Beché hammers, but the greater number, whilst still at about 1,000 ºC., pass directly into a set of scroll rolls which produce, in an ingenious manner, finished 3 in. balls direct from the 2 5/8 in. billets. Except in special cases, all balls are allowed to cool in the atmosphere and are not water quenched. Details of the Tests In order to enable the reader to evaluate properly the results and conclusions in the rest of the paper and in the discussions following the paper, most of the information presented by the author under this heading is quoted: ….. The testing unit was a nominal 30 in. diameter and 18 in. long centre discharge Denver Ball Mill. The ore pulp to the ball mill comprised a small portion of the normal feed to one of the fourteen City Deep 5 ft. 6 in. X 22 ft. tube mills, and the grinding media consisted of the balls under test plus other balls to give the desired load. The running time of the test-mill was divided into approximately equal periods of five days 13 ½ hours each. The usual procedure was to examine and make up the load

Jan 1, 1944

By G. R. Gray, T. S. Chapman, J. L. Foster

THE wall-building properties of salt-water drilling muds can be improved markedly by the addition of: (I) natural gums, such as tragacanth, karaya, and ghatti; (2) seaweeds, such as Irish moss; or (3) gelatinized starch. Results of laboratory tests have been confirmed by field trials. For drilling operations in which the mud becomes contaminated by salt, either through penetrating salt-bearing rocks or by addition of sea water to the mud, the added cost resulting from the use of one of the substances listed above is more than offset by freedom from stuck drill pipe and ease in running casing. INTRODUCTION It has been recognized for many years that oil production might be seriously hampered by infiltration of water from the drilling mud.1-4 As knowledge of the mechanism of the wall-building process advanced, methods were developed for evaluating the filtration characteristics of muds.5-11 The wall-building properties of fresh-water muds are commonly regulated by the addition of bentonitic clays, or of agents to promote the dispersion of the natural mud solids. When strata bearing soluble salts are encountered in the course of drilling, the salts are incorporated in the mud; the clay solids are flocculated and water loss is increased tremendously. Methods generally used in controlling filtration of fresh-water muds are no longer applicable. The problem of reducing water loss from salt-water muds is not confined to any particular area, but is acute in parts of West Texas. Salt beds several hundred feet thick must be penetrated before the oil-bearing formation is reached. Since the formation drilled does not provide mud-making material, it is necessary to use large quantities of commercial clays, and even the best commercial clay does not afford relief from the problem of high filtration. A laboratory study has been made of methods of improving the filtration characteristics of salt-water muds, and some of the methods have been used in field practice. LABORATORY INVESTIGATIONS Procedure Inasmuch as the immediate object of the investigation was the development of means of improving the wall-building properties of muds used in West Texas, an attempt was made to employ muds in the laboratory study comparable to those in field use. Samples of muds used in drilling the producing formations in six wells were secured. The properties of these samples are summarized in Table I, which lists the densities, viscosities, filtrations, and analyses of the filtrates for calcium, chloride, and sulphate. Viscosity was measured in the Stormer viscosimeter at 600 r.p.m. Water loss was determined at 80°F. with the Baroid low-pressure wall-building tester' at a pressure of 10o lb. per sq. in. Filtration rates are considerably higher than those of usual fresh-water muds, which amount to about 20 c.c. in 30 min. Water loss was so rapid in samples 4, 5 and 6 that filtration was complete in less than 10 min. and the values for 30 min. were extrapolated from the rates at shorter

Jan 1, 1941

By M. T. Hepworth, A. K. Stewart

Iron containing 0.1 pct A1 and -0.9 pct P by weight was internally oxidized in the temperature range 900° to 1300° C, where the bcc structure is stabilized by phosphorous. By measuring the depth of penetration of oxygen with time in an internally oxidized zone for an imposed surface oxygen potential, oxygen permeability was determined. The dgfusion coefficient of oxygen in iron was then calculated using known solubility data, yielding the expression: where Do is the diffusion coefficient of oxygen in bcc iron in sq cm per sec and T is temperature in OK. RECENTLY Hepworth, Smith, and Turkdoganl measured the diffusivity of oxygen in bcc iron and reported the temperature dependence of diffusivity from data determined in the a, and 6 temperature ranges. Subsequently Swisher and Turkdogan' have measured the diffusivity of oxygen in fcc iron. Internal oxidation techniques were employed by these investigators and in this current study. The analysis of this technique is developed by wagner3 (presented in English by Hauffe4 and Rapp 5). In this present study bcc iron stabilized by phosphorous was used to determine oxygen diffusivity in the temperature range 900° to 1300°C. Meijerin 6 has studied oxygen permeability in this temperature range using bcc iron stabilized with 5 pct Sn. Other inves- tigators who have studied oxygen permeability in bcc iron at other temperatures are Schenck et al., 7 Bohen-kamp and Engell, 8 and Bradford. EXPERIMENTAL Electrolytic iron of 99.99 pct purity was alloyed to contain 0.897 pct P and 0.093 pct Al. The maximum weight percent phosphorous required to stabilize bcc iron between 910" and 1392°C is 0.51 pct as determined by Haughton,10 0.42 pct by Roquet and jegaden," and 0.58 pct by vogel,12 with the latter value preferred by Hansen.13 Microprobe analysis indicated that there was no segregation of the phosphorous either before or after permeability studies; therefore, the quantity of phosphorous added was assumed to be sufficient to stabilize the bcc structure. Furthermore, the permeability results of studies on this alloy agreed substantially with interpolated values from previous data on bcc iron.' An ingot of the Fe-P-A1 alloy was hot-rolled to a l-in.-thick slab. Specimens were machined to dimensions: 13/8 by $ by 1/4 in. The experimental apparatus and procedure used have been described before.' A constant oxygen potential was established by passing argon and hydrogen through a column of oxalic acid dihydrate, which has a water vapor pressure which is well-known as a function of temperature. Slab specimens were exposed to a gas mixture sufficiently lean in oxygen to prevent the formation of a surface oxide for predetermined temperature for selected times. The specimens were then quenched, sectioned, and examined metallo-graphically. All quenched specimens were iron-plated to provide protection from the outside sample edge during polishing. Fig. 1 shows a typical microstruc-ture for a specimen oxidized at 953°C for 48.00 hr at a water vapor-to-hydrogen pressure ratio of 0.20. DISCUSSION AND RESULTS The following equation was derived by Hepworth et al.' from Wagner's kinetic expressions for internal oxidation:

Jan 1, 1969

By T. K. Prentice

The January-February number of the Journal of the Chemical Metallurgical and Mining Society of South Africa, 1943, is made up entirely of a discussion of Ball Wear in Cylindrical Mills. Following the principal paper by T. K. Prentice are several remarkably pertinent and carefully prepared discussions. Few persons in this country would be likely to see this publication, and since the information presented is new and of current interest, it seems desirable to abstract and review this publication for the benefit of the members of the A.I.M.E. The purpose of the investigation is stated in the first two paragraphs of Prentice's paper, as follows: Early in 1941, The Chamber of Mines Steel Products, Limited, initiated a series of tests under semi-working scale conditions to determine, if possible, those physical and chemical properties of a ball which make it resistant to wear when used in a cylindrical mill as a grinding medium, with the primary object of incorporating those beneficial qualities in the balls being produced at their works. This paper describes the tests carried out and discusses the results obtained. From these results it was possible to formulate a new theory relating to ball wear in cylindrical mills. This theory is presented in the second portion of this paper. Practical Ball-mill Tests in a Cylindrical Mill Part I of the paper begins with a discussion of the methods used for the manu- facture of grinding balls in South Africa. The following paragraph is of particular interest. The cast steel ingots, 4¼ in. square by 3 ft. 6 in. long, are re-heated in a gas-fired sloping stationary-hearth furnace and then rolled in a six-pass continuous mill into 25/8 in. round billets. Some of these billets are then removed and cut into suitable lengths for forging into 4 in., 3¼ in. , 3 in. or 2½ in. balls by means of three Drop and two Beche hammers, but the greater number, whilst still at about 1,000, pass directly into a set of scroll rolls which produce, in an ingenious manner, finished 3 in. balls direct from the 25/8 in. billets. Except in special cases, all balls are allowed to cool in the atmosphere and are not water quenched. Details of the Tests In order to enable the reader to evaluate properly the results and conclusions in the rest of the paper and in the discussions following the paper, most of the information presented by the author under this heading is quoted: The testing unit was a nominal 30 in. diameter and 18 in. long centre discharge Denver Ball Mill. The ore pulp to the ball mill comprised a small portion of the normal feed to one of the fourteen City Deep 5 ft. 6 in. X 22 ft. tube mills, and the grinding media consisted of the balls under test plus other balls to give the desired load. The running time of the test-mill was divided into approximately equal periods of five days 13½ hours each. The usual procedure was to examine and make up the load

Jan 1, 1947

By T. K. Prentice

The January-February number of the Journal of the Chemical Metallurgical and Mining Society of South Africa, 1943, is made up entirely of a discussion of Ball Wear in Cylindrical Mills. Following the principal paper by T. K. Prentice are several remarkably pertinent and carefully prepared discussions. Few persons in this country would be likely to see this publication, and since the information presented is new and of current interest, it seems desirable to abstract and review this publication for the benefit of the members of the A.I.M.E. The purpose of the investigation is stated in the first two paragraphs of Prentice's paper, as follows: Early in 1941, The Chamber of Mines Steel Products, Limited, initiated a series of tests under semi-working scale conditions to determine, if possible, those physical and chemical properties of a ball which make it resistant to wear when used in a cylindrical mill as a grinding medium, with the primary object of incorporating those beneficial qualities in the balls being produced at their works. This paper describes the tests carried out and discusses the results obtained. From these results it was possible to formulate a new theory relating to ball wear in cylindrical mills. This theory is presented in the second portion of this paper. Practical Ball-mill Tests in a Cylindrical Mill Part I of the paper begins with a discussion of the methods used for the manu- facture of grinding balls in South Africa. The following paragraph is of particular interest. The cast steel ingots, 4¼ in. square by 3 ft. 6 in. long, are re-heated in a gas-fired sloping stationary-hearth furnace and then rolled in a six-pass continuous mill into 25/8 in. round billets. Some of these billets are then removed and cut into suitable lengths for forging into 4 in., 3¼ in. , 3 in. or 2½ in. balls by means of three Drop and two Beche hammers, but the greater number, whilst still at about 1,000, pass directly into a set of scroll rolls which produce, in an ingenious manner, finished 3 in. balls direct from the 25/8 in. billets. Except in special cases, all balls are allowed to cool in the atmosphere and are not water quenched. Details of the Tests In order to enable the reader to evaluate properly the results and conclusions in the rest of the paper and in the discussions following the paper, most of the information presented by the author under this heading is quoted: The testing unit was a nominal 30 in. diameter and 18 in. long centre discharge Denver Ball Mill. The ore pulp to the ball mill comprised a small portion of the normal feed to one of the fourteen City Deep 5 ft. 6 in. X 22 ft. tube mills, and the grinding media consisted of the balls under test plus other balls to give the desired load. The running time of the test-mill was divided into approximately equal periods of five days 13½ hours each. The usual procedure was to examine and make up the load

Jan 1, 1947

By H. Papazian, Robert A. Lad

SINCE it can be shown both theoretically'' : and experimentally that disordered Cu3Au has a greater internal energy than the ordered alloy, it might be expected that its chemical reactivity would be greater. Experiments were initiated' to test this hypothesis. This note will describe some recent results obtained in the study of the rates of corrosion of ordered and disordered polycrystalline Cu3Au by aqueous FeCl., The work of Robertson' has indicated that the attack by such solutions is intergran-ular and highly orientation dependent. It was of interest to see whether the order-disorder effect was great enough to overcome the variations from specimen to specimen which would arise from this type of attack. The polycrystalline alloy specimens (0.020 in. wire, 1¾ in. long) were preannealed in ½ atm H, at 700°C for 2 hr. The subsequent heat treatments to produce order and disorder were performed in M atm He. Disordered specimens were obtained by heating at 450°C for 2 hr and quenching in water. Ordered specimens were produced by heating for 2 hr at 450°, furnace cooling to 380°, and soaking at 380°C for 80 to 90 hr. Room temperature was reached by cooling to 150" at a rate never exceeding 7" per hr, and water quenching from 150°C. The specimens so produced exhibited electrical resistivities characteristic of the two states; of the order of 11.27x10 ohm-cm for the disordered, and 4.28x10 ohm-cm for the ordered specimens. The corrosion rates were studied at 30°C in ferric chloride solutions of several concentrations (?,¼, 1.5, and 1 molar). The specimens were attached to a stirrer during the tests. Tests were interrupted at intervals, and the specimen weight change was determined after washing and drying. Analysis of the solutions showed that the attack was limited to the copper. The higher corrosion rate for the disordered alloy, as illustrated in Fig. l, is typical of the results obtained. The effect of variation in ferric chloride concentrations is indicated in Table I for typical specimens. The variations in the ratio of reactivity for disordered and ordered specimens at the different concentrations are within experimental error, and the best value is estimated to be near 1.4. The experimental variation was due in part to the mode of attack, as mentioned, and in part to the fact that films were formed on the specimens under some conditions. Electron diffraction patterns of the films were very complex and indicated the presence of metallic iron, as did chemical analysis. In an attempt to eliminate the difficulties arising from the mechanism of attack, single crystal specimens were used. A greater reaction rate was again measured for the disordered specimens, but the reproduci-bility was no better than that for the polycrystalline metal. This would indicate that film formation was primarily responsible. It was concluded that the reaction with aqueous ferric chloride served to demonstrate that the reactivity of disordered Cu3Au is greater than that of the ordered alloy. However, the difficulties with film formation did not permit determinations of a precision great enough to warrant extension of the study to partially ordered alloy systems.

Jan 1, 1957

By R. A. Stauffer

The chief ore of lithium is spodumene, a lithium-aluminum silicate containing up to 3 pct lithium. The preparation of lithium salts from spodumene is costly because of the low concentration of the metal and the difficulty of separating it from the other alkali metals present. Dr. Kroll's and Dr. Schlecten's recent paper1 has reviewed various methods proposed for preparation of lithium. It will be seen from this paper that the methods proposed to date have required one or another of the lithium salts as a raw material. The high cost of these salts has been the chief item of expense in the lithium metal produced. This situation has made it interesting to investigate the possibility of producing the metal directly from spodumene. When spodumene is calcined at 1000ºC in the presence of lime, lithium oxide is replaced in the ore as is evidenced by the fact that it may be leached from the reaction mixture with water.2 Free energy calculations suggested that lithium oxide might be reduced with aluminum or silicon and the lithium produced distilled from the reaction mixture by heating-to about 1000ºC in a vacuum. These facts taken together suggested that it might be possible to prepare lithium metal directly from spodumene by heating a mixture of the ore, lime, and a suitable reducing agent in vacuum and distilling off the lithium metal as formed. The Replacement of Li2O in Spodumene A series of experiments were undertaken to determine the ratio of lime to spodumene necessary to free substantially all the lithium oxide Present in the Ore. The spodumene used in these experiments was supplied by Foote Mineral Co. in the form of powder of about 200 mesh' Analysis of the spodumene was as follows: PCT SiO2......................... 62.7 Al2O3........................ 29.9 Li2o......................... 4.9 Na2O........................ 0.89 CaO......................... 0.75 MgO........................ 0.49 K2O......................... 0.44 Lime (cp —200 mesh) was added in various ratios to spodumene and thoroughly mixed in a ball mill. Two hundred gram samples of spodumene-lime mixtures were charged loosely in fireclay crucibles and held at 1000ºC in a gas-fired furnace for 5 hrs. The product in each case was ground to pass 140 mesh and then placed in a thimble in a soxhlet extractor. Extraction with water was carried on for 6 hrs. After this period the extract was reduced in volume by evaporation in order to precipitate dissolved lime and was then filtered and titrated with 1/4 normal hydrochloric acid. After correcting for residual calcium oxide in solution, the alkali present was calculated as lithium oxide. The results of these experiments are shown in Table I and Fig I. At lime-spodumene ratios less than 1.5, the products were invariably fused. At the ratio of 1.5 and above, the product was loosely sintered with little evidence of fusion. When the ratio of lime to spodumene was three, replacement of alkali oxides in the

Jan 1, 1949

By P. Beardmore, A. H. Holtzman, M. B. Bever

Specimens of the alloy CU3AU in the ordered and disordered states were subjected to explosive loading at shock pressures in the range from 160 to 475 kbars. The resulting changes in the resistivity, stored energy, microhardness, and microstructure were determined. By comparing the effects of explosive loading on ordered and disordered specimens a separation of structura1 and configurational changes has been made. In the pressure range from 290 to 370 kbars, representing a small increment of strain, the degree of long-range order in the ordered alloy decreased sharply. This change is attributed to the generation of shear stresses in excess of the theoretical shear strength of the alloy. Disordered CU3AU under explosive loading behaves in a manner considered to be characteristic of fee solid-solution alloys generally. The response of metals to high-velocity deformation and, in particular, to explosive loading has attracted much interest in recent years.' In general, metals are substantially strengthened by the passage of shock waves although the permanent strains are small. Explosive loading induces this strengthening by causing the metal to undergo rapidly a transient strain in a narrow region, first in the shock front and then in the rarefaction wave, which releases the pressure. The transient strain is given by e = 4/3 In V/Vo, where Vo and v are the specific volumes in the uncompressed and compressed states.2 The process produces many defects, which account for the strengthening. For the investigation reported here, an ordered alloy was chosen because it was expected to give sensitive indications of the near-neighbor effects produced by shock waves. The ordered alloy CU3AU was of special interest because of past work on the effects of conventional deformation on this alloy.314 The disordered alloy was included as a standard for comparison and as an alloy typical of a solid solution containing short-range order. The effects of explosive loading were followed by measurements of the resistivity, stored energy, and microhardness, and by metallographic examination. EXPERIMENTAL PROCEDURES Preparation of Specimens. Part of an ingot of the alloy Cu3Au prepared previously4 was cold-rolled with several intermediate anneals in vacuum to a final thickness of 0.042 in. Specimens of dimensions 2.0 by 1.0 by 0.042 in. were machined from this strip. After a recrystallization treatment of 1 hr at 565oC, half of the specimens were disordered by heating in evacuated Pyrex capsules for 1 hr at 460°C and quenching into water. Although they contained short-range order, they will be referred to as 'disordered" to indicate the absence of long-range order. The rest of the specimens were cooled slowly from 380°C to induce long-range order. The grain size of the ordered and disordered specimens was 0.012 mm. Explosive Loading. This was carried out at the Eastern Laboratory, Explosives Department, E. I. du Pont de Nemours & Co., by a driver-plate procedure described elsewhere.2 Two ordered specimens were stacked alongside two disordered speci-

Jan 1, 1964

By Nicholas J. Grant, Bill C. Giessen

The phase diagram Ta-Ni has been treated repeatedly; investigations up to 1958 are summed up in Ref. 1. Since then, an equilibrium diagram has been presented by Kornilov and Pylaeva.2 They found the following intermediate phases: Ta2N; (CuA12 type),3 "TaNi" (p phase, Mo8Co7 type), TaNiz, and TaNi3 (Ticus type).5 Of these, the crystal structure of TaNin remained unknown, and no further literature reference was found. According to Kornilov and pylaeva,&apos; TaNil melts peri-tectically at 1420°C. A 5-g alloy of Ta + 66.7 at. pct Ni was prepared by inert-gas arc melting using 99.95 pct Ta rod (NRC-MG) and 99.9 pct Ni shot (Fisher). The weight loss after three melts was <2 mg; a microscopically homogeneous ingot resulted. As shown in Ref. 6, no oxygen or impurity pickup needed to be considered under these conditions. Specimens were annealed for 15 hr at 1350°C, 15 hr at 1205oC, and 15 hr at 875°C with subsequent powdering and stress relief for 10 min at 1350°C, 15 min at 1205oC, and 1 hr at 875oC, respectively. Micrographs and X-ray analysis (114.6 mm Norelco camera, filtered CuK, radiation) showed homogeneous one-phase alloys in the as-cast state and at all three temperatures, all having the same powder pattern except for broad lines in the as-cast state. From this it is concluded that either TaNi, melts congruently or its melting behavior is a transition between the eutectic and peritectic cases. Since it was found that very slight surface contamination on stress relieving can considerably alter the structure of similar phases (e.g.,TaPt3),7 patterns before and after stress relief were also compared; they were identical except for line broadening in the non-stressrelieved condition, and two faint impurity lines in the stress-relieved samples. The powder pattern is presented in Table I. All lines were accounted for by indexing with a tetragonal lattice, 0Yh- I4/mmm , with a, = 3.154 ± 0.001A, co = 7.905 * 0.002i and c/a = 2.506. The atomic positions are: 1000; 1/2, 1/2, 1/2] + 2Ta(a): 000; + 4Ni(e): *(002); z = 0.333 * 0.002 This proves TaNi2 to be a representative of the MoSiz (Cllb) type. The variable parameter was determined by grouping the visually estimated intensi- ties according to their 2 indices, plotting their F values, and varying z for best fit, which was obtained at z = 0.333= 1/3. Since absorption was not considered, only the relative intensities with similar 28 can be expected to agree. The interatomic distances are presented in Table 11; the standard error is *o.o2A, resulting chiefly from the uncertainty in z. These distances indicate a coordination number 10 for both kinds of atoms and show that the pseudohexagonal layers along (110) are rather un-distorted. The mean atomic volume of 13.1A3 is close to the Vegard&apos;s law value of 13.3A3, showing

Jan 1, 1964