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By G. R. Rubly, H. J. Steele

LOCATION AND HISTORY THE San Manuel property is in townships 8S and 9S, range 16E, Gila and Salt River Base and Meridan, State of Arizona. This area is in the Old Hat mining district, southern Pinal County, and is about 3;2 miles southwest of the town of Mammoth on the San Pedro River and one mile south of the Mammoth mine at Tiger, Arizona. The property consists of over 150 contiguous lode claims. The Old Hat district was prospected prior to the Civil War, but there was little or no production until 1881.1 The chief producers have been the Mammoth and Mohawk mines, now consolidated and operating as the St. Anthony Mining and Development Co., Ltd. Production to 1936 was $5,200,000, of which 83 pet was gold.2 Since 1940 the production has been chiefly lead and zinc, and some molybdenum and vanadium. There are a few small properties in the vicinity that have produced very minor tonnages of copper ore. In the San Manuel group there are claims which have been held continuously from 1906 to the present time, and at least two churn-drill holes were put down on or near the outcrop in 1917. No logs for these holes are available, but it is assumed that the grade of copper encountered was not sufficient to encourage further exploration. A small amount of ore has been shipped from open cuts on the San Manuel outcrop area, but there is no record of the tonnage or grade. It is estimated that not more than 5o tons were mined. These cuts, plus a few shallow shafts and some short adits indicate limited and unenthusiastic prospecting at San Manuel. In 1942, through the efforts of James M. Douglas, R. B. Giffin, Victor Erickson, and Henry W. Nichols, owners of the San Manuel group, the Reconstruction Finance Corporation and War Production Board authorized the United States Geological Survey to investigate the property, and by their recommendation, the United States Bureau of Mines was authorized to put down a limited number of churn-drill holes. The Bureau of Mines carried on drilling from November 1943 to February 1945. Seventeen holes were drilled, varying from 305 to 1990 ft in depth. The property was brought to the attention of Magma Copper Co. in June I944 and an option agreement was made with the owners. Subsequently, a group of claims lying north of the original group and held by the Apex Lead Vanadium Mining Corp., and a group to the east held by the Quarelli family, were optioned. A drilling program was laid out to conform to the Bureau of Mines pattern, and drilling started in December 1944. San Manuel Copper Corp. was incorporated September 1945, and has carried on the exploration program to the present time. GEOLOGY General The mineralized outcrop, chief copper mineral of which is chrysocolla, is a tri-

Jan 1, 1947

By F. S. McNicholas

IN the writer's opinion the term "block caving" has been rather loosely applied to a general principle of mining, and therefore detailed classification of caving methods and draw, together with the characteristics required for each method, will fill a desired need. Selection of caving method should be made only after a study of all governing conditions, such as size of orebody, lateral and vertical extent of ore-body, attitude, treatment demands, possible resultant pressures, and cost and profit comparison of methods. Successful caving methods can be classified under six main headings: (1) Full-protected block caving, (2) semi-protected block caving, (3) unprotected block caving, (4) full-panel caving, (5) half block-panel caving, (6) block-panel caving. The methods and factors governing choice of method are shown in Table I. Full-protected Block Caving Full-protected block caving consists of develop-ing, undercutting, and drawing to exhaustion a block of ore of predetermined size without coordination of mining or draw with adjoining areas. The block is mined and drawn as an independent unit (Fig. 1). Full-protected block caving demands that mining and draw cannot be done against unconsolidated capping in adjoining caved and exhausted blocks. Two sides of block are against solid. Caved capping must be allowed to consolidate for a suitable period, usually not less than one year. Pillars may be left in lieu of consolidated capping (Fig. 2). The advantages of full-protected block, caving are: (1) A definite area is developed, mined, and drawn as a unit so that all work may be completed, the block drawn to exhaustion in the minimum length of time, and the area then abandoned. (? Production is not restrained because of coordina1, on with adjoining areas. (3) Records of draw and caved reserve of ore are good. Upon abanwnment of the block, accountability for production is closed out with no carry-over to adjoining areas. The disadvantages of full-protected block caving are: (1) Side dilution from the draw adjacent to the consolidated capping may be serious, particularly where capping does not consolidate sufficiently in the allotted time. (2) Boundary weakening is needed on the solid sides of the block except in weak rocks. (3) Maximum cantilever and compression effect to aid caving and fragmentation may not be secured since the draw should proceed from the solid to the consolidated capping to minimize side dilution. However, undercutting from the loose (caved capping) to the solid with a slight initial draw in the same manner will develop cantilever effect. (4) A period of at least one year, more is usually desirable, must be allowed for caved capping ,to consolidate before mining the adjoining block, depending upon the characteristics of the capping. (5) Capping may not consolidate sufficiently in the time that can be allowed. Full-protected block caving is indicated where: (1) The ground is weak and heavy and workings

Jan 1, 1952

By Reed W. Hyde

Some information has been published on the sulphur dioxide concentration of gases from D wight-Lloyd machines sintering lead ores but most of this relates to the customary practice in which the charge is relatively high in lead and is sintered in two passes Over the machine. It is thought, therefore, that the following observations on sintering in one pass a low-lead, low-sulphur charge may be of interest. The data were obtained in sintering lead sulphide notation concentrates mixed with minus 20.mesh oxide ore, the mixture carrying 16,8 per cent Pb and 5.3 per cent S. No returns were used because of the limited amount of sulphur available as fuel, but the mixture pelletized readily. to make a satisfactorily permeable bed on the sintering machine. As there was a possibility that the SO z might be utilized, a series of runs was made to determine the concentration ofSO2 in the gases at different points along the wind box, and the effect on this concentration of changes in the wind-box vacuum. Several runs each were made with vacuums (as measured in inches of water at the wind box) of (1 2 to 1 in., ('1 4 to 3% in. and (3) 6 to 5% in. The averages of the determinations from each series are platted On the graph (Fig, 1). The vertical scale shows the percentage by volume of SOz (as determined by the Reich method), and the horizontal scale shows the time e~pressed as percentage of the total sintering time. Sintering was considered to be complete when no SOz could be detected in the gases. In all cases the depth of bed was 4 1/2 in. and the weight of dry charge per square foot of hearth area was 45.2 lb. Other data are given in the table. The volume of gases corresponding to the several points along the wind box at which SO2 determinations were made could not be measured, but has been calculated from the SO2 Content and sulphur elimination on the assumption that the volume is uniform throughout the sintering period. This is not strictly true, as with a given vacuum the volume usually will drop slightly toward the middle of the period and increase toward the end. However, this made is a reasonable approximation. several interesting features are brought out by these data. In general, the published data on SO 2 concentration in sintering under ordinary conditions show a high SO2 concentration in the early stages followed by a rapid decrease in concentration and with relatively little SOz in the gases from the last half or third of the operation. In other words, the greater part of the sulphur elimination is obtained in the first third or half of the period. In these runs, the 6-in. vacuum, which approximates the usual operating condition, gives a curve that follows this customary pattern. Maximum SO2 concentration is obtained 234 min. after

Jan 1, 1944

By AIME AIME

THE organization of the Board of Directors was effected Tuesday afternoon in ' executive session. Messrs. Bassett,. Buehler, Cates, Daveler, Eavenson, Eilers, Elliott, Evans, Guess, Lovejoy, Moulton, Rickard, Tally, Turner,, Wraith and Wright being pres¬ent. Messrs. Tally, Bassett, Rickard, Mathews and Cates were chosen to form the Executive Committe with Mr. Tally as Chairman, and Messrs. Krumb, Guess and Moulton for the Finance Committee with Mr. Krumb as chairman. Karl Eilers was reelected as Treasurer and H. Foster Bain as Secretary, after which the Directors adjourned for the usual dinner reported elsewhere. At the open session of the Board, at which in addition Messrs. Allen and McAuliffe were present, the work of organization was continued with appointments to committees as listed herewith. Various actions of the Executive and Finance Committees were confirmed, the budget for 1931 formally approved, the meeting dates for the year adopted, 34 new Members and Associates, 13 Junior Members and 31 Student Associates admitted by election and transfer and 29 resignations accepted.

Jan 1, 1931

By K. Barron

The glass insert stressmeter, or photoelastic stressmeter, is an instrument designed to determine stress changes occurring in rocks. It has several potential advantages over other such devices in that it is a biaxial device, it is simple and it is cheap to make. The object of this study was to assess the behaviour of the meter under biaxial loads and to examine some of the problems associated with measurement and interpretation of the fringe pattern. This assessment has been carried out by comparing theoretical and laboratory behaviour of the meter. It has been shown that: a) There are certain optimum measuring points in the meter at which measurements should be made for best accuracy. The position of the points depends on the ratio, n, of the biaxial stresses. b) The meter&apos;s sensitivity can be assumed to be independent of the rock modulus E provided that the rock modulus is < 2.5 x 106 psi and not, as previous workers have assumed, if E < 5 x 106 psi. c) There are several methods of separating the principal stresses; some of these are unsatisfactory. A new method is proposed and discussed. d) The meter sensitivity decreases as the ratio of the biaxial stresses approaches unity; the accuracy thus also decreases. e) The axes of symmetry of the fringe pattern give an excellent indication of applied stress direction. f) Laboratory calibrations are in good agreement with theory. The glass insert or photoelastic stressmeter is an instrument designed to determine stress changes occurring in rocks. It has several potential advantages over other such devices in that it is a biaxial device, it is simple and it is cheap to make. This stressmeter has been described in detail.l,2 Basically it is a hollow glass cylinder that has at one end a light source and filters producing circularly polarized light. The glass cylinder and source are grouted into a borehole in rock and the face of the cylinder is viewed through a quarter wave plate and an analyser. If, after installation, a stress change occurs in the rock, then a distinct colored isochro-matic fringe pattern is seen in the meter. The fringe order at any point in the meter can be determined by counting the fringes and measuring the fractional fringe orders by the Tardy compensation method. The relation between the fringe order at any point and the applied stress change can be determined either by calculation or by calibration. The object of this study was to assess the behavior of this stressmeter under biaxial loading conditions and to examine some of the problems of interpretation of the fringe pattern. THEORY Hiramatsu et a14 have determined the stress distribution in a hollow cylindrical inclusion in an elastic host material when subject to uniaxial stress. Using this solution, the biaxial case of stress p in the x direction and stress q in the y direction (Fig. 1) can be solved by superposition. This has been done in Appendix 1. It is shown that the principal stress difference (s1 -s2) at any point (r,?) in the cylinder is given by:

Jan 1, 1965

By L. M. Pidgeon, K. T. Aust

There has been considerable interest in the possible use of titanium in magnesium alloys.&apos; Zirconium has shown some promise in this connection2 and its general similarity with titanium suggests that the latter might act in a similar manner. A literature survey revealed that quantitative data on the Mg-Ti system was unavailable. Several patents3 have claimed that titanium additions from 0.2 to 4 pct to magnesium alloys were possible, but no mention was made as to the form in which the titanium existed in the alloy. Kro114 succeeded in introducing only traces of titanium into magnesium by bubbling TiCl4 through the metal under argon or by reacting it with sodium titanium fluoride. The application of theoretical data given by Carapella5 based on Hume-Rothery&apos;s principles, involving atomic size factor, crystal structure, valency and the electro-chemical factor, suggests that a Mg-Ti alloy is a favorable case, and the system appeared to warrant experimental examination. Experimental Procedure and Results THERMAL ANALYSIS If titanium is appreciably soluble in magnesium, a change in the melting point of the magnesium might be detectable using standard cooling curve methods. Magnesium was melted in graphite crucibles under an argon atmosphere, the assembly being enclosed in a silica tube. Graphite thermocouple protection tubes served also to stir the melts. The apparatus was very similar to Fig 1, with the addition of a refractory and baffle system to prevent undue heat losses from the top of the crucible. Chromel-alumel thermocouples were calibrated using Al of 99.97 pct purity. Dominion Magnesium Limited sup- plied redistilled high purity magnesium of the analysis given above. Titanium was added in three different forms: 1. Titanium powder —100 mesh, from the Titanium Alloy Manufacturing Co., Niagara Falls, N. Y. 2. Sheet titanium from the U.S. Bureau of Mines, produced by Mg reduction of TiCl4. 3. Magnesium —50 pct titanium master alloy from Metal Hydrides Inc., Beverly, Mass. The melting point of the high purity magnesium used was measured experimentally as 651.0°C. More than a dozen tests were conducted using titanium from the three sources referred to above, in calculated additions up to 20 pct titanium, at temperatures between the melting point and 1000°C and holding periods up to 6 hr. In no case was evidence obtained of solubility of titanium in magnesium, using inverse-rate and time-temperature curves. The melting point of the magnesium was unchanged within the accuracy of measurement, namely -+0.5°C; and no other thermal arrests were detected. Metallographic investigation of the thermal analysis billets indicated that the titanium additions were apparently mechanically entrapped in the magnesium in segregated areas. Consequently, these samples were not analyzed for titanium. The master alloy proved to be a mechanical mixture of titanium particles in a magne- sium matrix. These results indicated that the titanium solubility, if such existed, could not be obtained by the usual thermal methods. X RAY DIFFRACTION INVESTIGATION In an effort to detect solubility of titanium in magnesium, samples were investigated using both the Debye-Scherrer and the Focusing Back-Reflection methods. Filings from samples of the thermal analysis billets and from pure magnesium were annealed in argon one hour at 350°C to relieve mechanical strain. Measurements made of the interplanar spacings showed no difference between the Mg-Ti samples and pure magnesium. The interplanar spacings could be measured to within 0.0002A, and the greatest variation found was 0.0004A, in the back-reflection method. The diffraction lines for magnesium were not shifted by the titanium additions indicating that the solid solubility of titanium in magnesium is of a very low order—less than 0.5 pct. From both diffraction methods, a d or interplanar spacing of 0.817A was obtained for the redistilled high purity magnesium. This latter value is not given in the standard X ray diffraction cards for magnesium metal or vacuum distilled magnesium. Theoretical calculations for a close-packed hexagonal space lattice for magnesium indicate that the planes {2134) should give a line which was found. The relative intensity for this reflection at 0.817A is slightly less than that at 0.870k for magnesium. SOLUBILITY OF TITANIUM IN LIQUID MAGNESIUM The Mg-Mn system was examined by Grogan and Haughton6 who were

Jan 1, 1950

Mine Transitman.-Engineer, about 30 years of age, experienced in coal mine underground surveys. Must be good draftsman and possess sufficient personality to get results from the men. Location, Illinois. No. R 419. Coal Mining Engineer: Coal mining engineer of proved ability for position of manager f high-grade bituminous coal property. Location, Canada. No. R 427. Chemist or Metallurgical Engineer.-Chemist or metallurgical engineer for special library work. Man with scientific training with the ability and education -of a young instructor in a university. Duties would consist of working out a new method of indexing scientific information, more particularly in obtaining information for use of a Committee on the Heat Treatment f Steel. Location, Washington, D. C. No. R 470. Topographical Draftsman.-Civil engineering training and topographical and surveying experience. Unmarried man, under 40 years of age. Knowledge of Spanish not necessary. Discharged army or navy man preferred. Location, oil fields, Mexico. Salary, $5 per day, living and traveling expenses. No. R 483. Mechanical Draftsman.-Engineering training, familiarity with drawings of pumps, piping, etc., need not necessarily be a designer. Unmarried man, under 40 years of age. Discharged army or navy man preferred. Location, Mexico. Salary $5 per day with living and traveling expenses. No. R 484. Engineer Translator.-Engineer of Portuguese nationality who has received his technical training abroad, and has been filling engineering positions in this country, to translate material for catalogs of an engineering character. No. R 486.

Jan 5, 1919

By John Griffen, David H. Davis

Much of the ground to be covered by this paper was ably covered by a paper presented by Messrs. Morrow and Jordan1 before a joint meeting of the Iron and Steel Section of the Engineers Society of West-ern Pennsylvania and the A.I.M.E. Pitts-burgh Section at Pittsburgh in the spring of 1940. As that paper was not published, the present authors have availed them-selves of Mr. Morrow&apos;s kind permission to use information given therein. Similar figures for the latest years available have been added to many statistics originally presented. It is unfortunate that Mr. Jordan&apos;s death removes his stimulating guidance and help, which the authors would have welcomed and have found invaluable in the past. One interested in the Pittsburgh seam should not fail to read the exhaustive and authoritative paper by Eavenson2 presented in 1938. As Allegheny, Fayette, Greene, Washington, and Westmoreland Counties contain practically all the reserves and furnish nearly all of the production from the Pittsburgh seam in Pennsylvania at the present time, this area only is intended when reference is made to the Pittsburgh seam in Pennsylvania. On much of the seam in Greene and Washington Counties, which contain a large proportion of the total reserves, insufficient data are available to determine the detailed characteristics of the seam with any degree of finality. It is hoped that the data presented here will fairly well indicate the probable characteristics. Economic Importance of the Pittsburgh Seam The Pittsburgh seam in Pennsylvania is of primary importance as a coal resource, not only because of its substantial reserves but because it contributes such a large proportion of the coal used in the country and an even larger proportion of that used in the manufacture of coke. Mr. Ashley3 placed the estimated recoverable reserves (1935) of the Pittsburgh coal bed in Pennsylvania at 7,500,000,000 tons.* Although a considerable portion of this tonnage is not now suitable for coking coal, because of its high sulphur content, undoubtedly the supply of coking coal will last for many years and that not suitable for coking will furnish industry with an ample supply of energy. In attempting to assess the contribution of the Pittsburgh seam to total coal production and to that of coal used in making coke, one finds that the statistics published annually by the U. S. Bureau of Mines, Minerals Yearbook, do not give tonnages classified as to seams but only as to districts or states and counties. However, it happens that, at present and during much of the

Jan 1, 1944

By David H. Davis, John Griffen

Much of the ground to be covered by this paper was ably covered by a paper presented by Messrs. Morrow and Jordan1 before a joint meeting of the Iron and Steel Section of the Engineers Society of West-ern Pennsylvania and the A.I.M.E. Pitts-burgh Section at Pittsburgh in the spring of 1940. As that paper was not published, the present authors have availed them-selves of Mr. Morrow&apos;s kind permission to use information given therein. Similar figures for the latest years available have been added to many statistics originally presented. It is unfortunate that Mr. Jordan&apos;s death removes his stimulating guidance and help, which the authors would have welcomed and have found invaluable in the past. One interested in the Pittsburgh seam should not fail to read the exhaustive and authoritative paper by Eavenson2 presented in 1938. As Allegheny, Fayette, Greene, Washington, and Westmoreland Counties contain practically all the reserves and furnish nearly all of the production from the Pittsburgh seam in Pennsylvania at the present time, this area only is intended when reference is made to the Pittsburgh seam in Pennsylvania. On much of the seam in Greene and Washington Counties, which contain a large proportion of the total reserves, insufficient data are available to determine the detailed characteristics of the seam with any degree of finality. It is hoped that the data presented here will fairly well indicate the probable characteristics. Economic Importance of the Pittsburgh Seam The Pittsburgh seam in Pennsylvania is of primary importance as a coal resource, not only because of its substantial reserves but because it contributes such a large proportion of the coal used in the country and an even larger proportion of that used in the manufacture of coke. Mr. Ashley3 placed the estimated recoverable reserves (1935) of the Pittsburgh coal bed in Pennsylvania at 7,500,000,000 tons.* Although a considerable portion of this tonnage is not now suitable for coking coal, because of its high sulphur content, undoubtedly the supply of coking coal will last for many years and that not suitable for coking will furnish industry with an ample supply of energy. In attempting to assess the contribution of the Pittsburgh seam to total coal production and to that of coal used in making coke, one finds that the statistics published annually by the U. S. Bureau of Mines, Minerals Yearbook, do not give tonnages classified as to seams but only as to districts or states and counties. However, it happens that, at present and during much of the

Jan 1, 1944

By R. F. Mehl, C. S. Barrett, A. H. Geisler

THE mechanism by which the super-saturated solid solution of 20 per cent silver in aluminum decomposes has been reported in two previous publications. 1,2 The analysis of streaks in Laue photograms showed that thin platelike particles (the so-called Guinier-Preston aggregates) form upon {111} matrix planes in the early state of decomposition.1 The size of these particles is larger, the higher the temperature at which they form in accordance with nucleation theory;3 at all temperatures they increase in size with aging.2 When they have grown thick enough to afford three-dimensional diffraction, powder X-ray photograms show that the structure is not that of the equilibrium precipitate y but that of a transition lattice ?&apos;. Since this is also platelike in shape and also lies upon the {111} matrix planes with the {110} direction in the matrix parallel to the {11.0} direction in ?&apos;, it seems likely that the original platelet particles are merely ?&apos; in an early stage of formation, and thus finely dispersed. The atomic spacing and pattern on the {00.0} plane in ?&apos; are identical with those on the {111} matrix plane to which it lies parallel, and since comparable directions in the two planes are parallel, the lattices are thus coherent at the interface; an analogous coherence has been found in aluminum-copper alloys.3 The structures ?&apos; and y are both close-packed hexagonal and are oriented alike; they differ only in interatomic distances. Consequently, ? &apos; is regarded as y strained from its ordinary dimensions by the lattice coherency between it and the matrix.2 The lattice movements that transform the matrix to the equilibrium precipitate appear to be very simple.2 The mechanism of precipitation in this system is simpler and is more precisely known than that in any other system,2,4 hence the system should be a profitable one for the difficult task of correlating property changes with structural alterations. The present report provides additional studies on powder X-ray diffraction from alloys of 10 per cent, 20 per cent and 30 per cent Ag, and presents the correlation of crystallographic changes with changes in microstructure, Brinell hardness and electrical resistivity of the three alloys. PREPARATION OF SAMPLES AND EXPERIMENTAL PROCEDURE The preparation of the 20.2 per cent Ag alloy has been described.2 Alloys containing 9.9 and 29.7 per cent Ag were prepared from 99.97 per cent Al and 99.99+ per cent Ag using a similar procedure. Rolled

Jan 1, 1943

By D. K. Crampton, H. I. Burghoff, J. T. Stacy

The effect of cold-working upon electrical conductivity of copper and of copper alloys appears not to be generally known in detail. Although several papers on the subject have been presented, showing variable effects according to alloy composition, it is often assumed that the 2 to 3 per cent lowering of the conductivity of ordinary tough-pitch copper by severe cold-working is typical for copper alloys. Because of this situation it was decided to carry out the present work upon several types of copper, copper-zinc alloys over the commercial range of brasses, other binary alloys, and numerous age-hardening alloys in the quenched, and quenched and aged conditions. The large number of alloys investigated made it impossible to study every one in the detail it may have merited. Inasmuch as several interesting points that could not be satisfactorily explained came to light, further work is contemplated by the authors. It is usually considered that the normal effect of cold-work on ductile metals and unordered alloys is to decrease conductivity slightly. In alloys that are in the ordered state, as annealed or otherwise heat-treated, cold--working tends to disorder the structure, resulting in very marked lowering of conductivity. The random state of atomic arrangement produces lower con- ductivity than the ordered state for the same composition.1 Previous Work Previous work in the authors&apos; laboratory has shown the electrical conductivity of several copper alloys to be decreased by greater amounts than might have been expected, in view of the general knowledge on the subject, when cold-worked. Guillet and Ballay2 investigated the influence of cold-work upon the resistivity of several metals and alloys, including copper and some copper alloys. The increase of resistivity due to severe working w is less than 4 per cent for all pure metals tested, while the increases for the alloys were generally higher. In the copper-zinc alloys, they found that the increase of resistance due to drawing increased with zinc content, and reported a 21.7 per cent increase of resistance for an alloy contaiiiing 67.9 per cent Cu as severely worked. Masima and Sachs3 studied the change in electrical resistance of three brass crystals when stretched in the tensile test, obtaining increases in resistance of the order of 3 per cent for 30 to 40 per cent reduction of area of the specimens. The resistance decreased again when the cold-worked crystals were subsequently annealed. Bardenheuer and Schmidt4 found that the conductivity of copper was decreased by 3 to 4 per cent when reduced 50 per cent by working. The conductivity of 72-28

Jan 1, 1941

By D. K. Crampton, H. I. Burghoff, J. T. Stacy

The effect of cold-working upon electrical conductivity of copper and of copper alloys appears not to be generally known in detail. Although several papers on the subject have been presented, showing variable effects according to alloy composition, it is often assumed that the 2 to 3 per cent lowering of the conductivity of ordinary tough-pitch copper by severe cold-working is typical for copper alloys. Because of this situation it was decided to carry out the present work upon several types of copper, copper-zinc alloys over the commercial range of brasses, other binary alloys, and numerous age-hardening alloys in the quenched, and quenched and aged conditions. The large number of alloys investigated made it impossible to study every one in the detail it may have merited. Inasmuch as several interesting points that could not be satisfactorily explained came to light, further work is contemplated by the authors. It is usually considered that the normal effect of cold-work on ductile metals and unordered alloys is to decrease conductivity slightly. In alloys that are in the ordered state, as annealed or otherwise heat-treated, cold--working tends to disorder the structure, resulting in very marked lowering of conductivity. The random state of atomic arrangement produces lower con- ductivity than the ordered state for the same composition.1 Previous Work Previous work in the authors&apos; laboratory has shown the electrical conductivity of several copper alloys to be decreased by greater amounts than might have been expected, in view of the general knowledge on the subject, when cold-worked. Guillet and Ballay2 investigated the influence of cold-work upon the resistivity of several metals and alloys, including copper and some copper alloys. The increase of resistivity due to severe working w is less than 4 per cent for all pure metals tested, while the increases for the alloys were generally higher. In the copper-zinc alloys, they found that the increase of resistance due to drawing increased with zinc content, and reported a 21.7 per cent increase of resistance for an alloy contaiiiing 67.9 per cent Cu as severely worked. Masima and Sachs3 studied the change in electrical resistance of three brass crystals when stretched in the tensile test, obtaining increases in resistance of the order of 3 per cent for 30 to 40 per cent reduction of area of the specimens. The resistance decreased again when the cold-worked crystals were subsequently annealed. Bardenheuer and Schmidt4 found that the conductivity of copper was decreased by 3 to 4 per cent when reduced 50 per cent by working. The conductivity of 72-28

Jan 1, 1941

By M. Gell, G. R. Leveran

The high- and low-cycle fatigue properties of the nickel-base superalloy, Mar-MBOO, in columnar-grained and single-crystal forms were determined at room temperature. It was found that the fatigue lives of these materials were greatly affected by the size of preexisting cracks in MC-type carbides contained in the micro structure. Most of the data falls on two curves given by: (zN)&apos;/A€= K, where Nf is the number of cycles to failure, Af is the total strain range, and K is a function of carbide size. No difference was observed in the fatigue behavior of the columnar-grained and single-crystal materials for the same MC carbide size. Matrix slip and crack initiation occurred at precracked MC carbides and, to a lesser extent, at micropores. Fatigue crack propagation was mainly in the Stage I mode, i.e., on cry stallo graPhic slip planes. The Stage I fracture in these materials was unusual in that distinct features were observed on the fracture surfaces. In high-cycle fatigue, these features resembled those commonly observed on the cleavage fracture surfaces of bcc and hcp materials. Yet, in this study, the cracks propagated slowly in a cyclic manner. In low-cycle fatigue, the Stage I facets contained equiaxed dimples, similar to those observed on the tensile fracture surfaces of ductile materials. These observations indicate that both local normal and shear stresses are involved in these Stage I fractures. A model is proposed to explain these results based on the weakening of the cohesive energy of the active slip planes by reversed shear deformation and the fracture of the bonds across the weakened planes by the local normal stress. RECENT developments in casting technology have produced cast nickel-base superalloys in columnar -grained and single-crystal forms.1&apos;2 The tensile and creep properties of the nickel-base superalloy, Mar-M200, cast in these forms have been shown to be superior to the corresponding properties of the conventionally cast polycrystalline material.lp2 This improvement in properties results, in part, from the elimination of grain boundaries in the single crystals and the alignment of the grain boundaries parallel to the stress axis in the columnar-grained castings. As part of a program to evaluate the fatigue properties of nickel-base superalloys cast in single-crystal and columnar-grained forms, a study has been made of the cyclic deformation and fracture of Mar-M2OO at room temperature. M. fiFl I .hininr Mpmher AIMF ic ^pninr Rocoarrh Accn^iata anH I) EXPERIMENTAL PROCEDURE The composition range of Mar-Ma00 in weight percent is: 8 to 10 Cr, 9 to 11 Co, 11.5 to 13.5 W, 0.75 to 1.25 Cb, 1.75 to 2.25 Ti, 4.75 to 5.25 Al, 0.01 to 0.02 B, 0.03 to 0.08 Zr, 0.07 to 0.12 C, bal. Ni. All of the castings met the above specifications. The castings were solutionized for 1 to 4 hr at 2250°F followed by aging at 1600°F for 32 hr which resulted in a 0.2 pct offset yield stress of 150,000 psi at room temperature. The microstructure of the material consisted of cuboidal, coherent particles of ordered, fcc Ni3(A1,Ti) (commonly designated y&apos;), approximately 0.3 p on edge, distributed in an fcc y solid-solution matrix. MC carbides together with shrinkage and gas micropores were also distributed throughout the materials. The MC carbides and micropores were located preferentially in the interdendritic interstices, as well as in the grain boundaries in the columnar-grained castings. The (100) direction of all the single crystals and the common (100) axis of the grains in the columnar materials were aligned within about 5 deg of the specimen axis. Fatigue testing was carried out in the high-cycle (HCF) and low-cycle (LCF) fatigue regions, with the major difference being gross yielding of the specimen occurred during the first cycle in the LCF region. This division also corresponded with the more usual one in which the life of a specimen in LCF is less than lo4 cycles and that in HCF is greater than lo4 cycles. The designs of the high-cycle fatigue and low-cycle fatigue specimens are shown in Figs. l(a) and (c), respectively. The gage sections of both HCF and LCF specimens were electropolished prior to testing. The HCF specimens were tested in an MTS, closed-loop, hydraulic fatigue machine at 10 cps in air. The specimens were cycled between a tensile stress of 5000 psi and a maximum tensile stress which ranged from 35,000 to 125,000 psi, Fig. l(b). The LCF specimens were cycled under strain control from zero to a maximum tensile strain, Fig. l(d), in a Wiedemann-Baldwin testing machine. The experimental procedure has been described elsewhere.3&apos;4 Both HCF and LCF tests were interrupted periodically in order to replicate the development of slip and cracking at the specimen surface. This was accomplished by placing plastic replicating tape around the gage section of the specimen while the specimen was in the mahine. The size of the MC carbides for all specimens was measured on a polished longitudinal section through the gage section after fatigue testing. The method of measurement consisted of carefully scanning the entire polished section in order to locate the largest MC carbides. Photographs were then taken of the six longest carbides oriented approximately normal to the

Jan 1, 1969

By D. Turnbull, J. H. Hollomon, J. C. Fisher

UNDERSTANDING of the diffusion problem has recently been furthered by the analysis of Birchenall and Mehl.1 They pursued the problem of the variation of the diffusion coefficient with composition for non-ideal solid solutions. Their analysis follows the tradition of Wagner,2 Jost,3 Dehlinger,4 and Darken,&apos; who assumed the net flux of dif¬fusing material to be proportional to the gradient of a quantity related to free energy. The basic assumption in Birchenall and Mehl&apos;s formulation of the problem is that the net flux of diffusing material is proportional to a thermodynamic activity gradient. To estimate the applicability of the derived relations, they corrected the diffusion coefficients of carbon in austenite by utilizing Smith&apos;s&apos; activity data for carbon, and the diffusion coefficients for zinc in copper with activity data computed from the vapor pressure measurements of Hargreaves.7 The corrected coefficients for carbon were virtually independent of carbon concentration. For the diffusion of zinc in copper a moderate variation of diffusion coefficient with concentration remained after the correction. The problem of diffusion can be formulated in another way than that used by Birchenall and Mehl. The method is that of chemical rate theory and has been used by Eyring and his coworkers8,9 as well as by Eyring and Zwolinski10 in a discussion to Birchenall and Mehl&apos;s paper. As yet the method has not been applied to substitutional solid solutions. On the basis of their assumptions, Eyring and Zwolinski derived a relation between the diffusion coefficient and activity that is identical with that of Dehlinger and Darken but which does not correct for the variation of the diffusion coefficient with concentration as well as does the relation derived by Birchenall and Mehl. It was thought that the theory of diffusion would be more complete if the inconsistency between the two analyses could be rationalized and if diffusion in substitutional alloys were analyzed on the basis of the concepts of the chemical rate theory. CHEMICAL RATE THEORY According to the theory of absolute reaction rates8 the reaction [A,+A2+ ... +.A;->X,+X2 +...+X; EqI] is viewed as taking place in two steps. First the reactants A1, A2, . . . A[i] combine to form an activated complex M with which they are in equilibrium; [A, + A2 + .. . + Ai = M. Eq 2] Second the activated complex decomposes to give the products X1, X2. . .. X[j]; [M->X1+X2+ ... +.X;. Eq3] It has been shown8 that the number of activated complexes decomposing per unit volume per unit time is given by the expression† [kT]

Jan 1, 1948

By W. D. Robertson, E. Scala

Electrical resistivity of a number of pure liquid metals and alloys has been measured as a function of temperature and composition. The data show a close correspondence between the liquid and solid states with respect to thermal, structural, and compositional relationships. STUDY of diffuse scattering of X-rays by liquid metals1 has demonstrated that some degree of order persists above the melting point and that the atomic constitution of liquids is more analogous to the solid state than to a gas. Consideration of the change in various thermodynamic properties that accompanies transformation from solid to liquid leads to the same general conclusion.² evertheless, specific knowledge of the constitution of the liquid state is limited when compared with that of the solid and gaseous states owing, in part, to the difficulty of interpreting the X-ray data and in part to the indirect character of deductions based on thermodynamic data. Of the structure-sensitive physical properties, electrical resistivity of liquid metals is perhaps the most easily interpretable, particularly when comparison is made with the solid state. According to the available data, most of which was obtained prior to 1914, cubic metals exhibit a normal linear and positive temperature dependence in the liquid state and the data have been accepted without question. The divalent metals, zinc and cadmium, are apparently exceptional in that resistivity is not linear with temperature and it passes through a minimum. Mercury also exhibits a nonlinear temperature dependence but the slope is always positive. Important comparisons with magnesium could not be made at the time the following work was undertaken because the necessary experimental data were not available. Data on liquid solutions are very limited and are largely from a single source."-" Based on Bornemann&apos;s work, Norbury7 pointed out that the resistivity of liquid copper alloys appeared to be dependent on the valence of the solute and that the increase due to the solute was of the same order as in the solid state. However, large extrapolations were involved and no quantitative relationship was developed. Therefore, before proceeding with additional deductions regarding the resistivity of liquid metals and interpretation in terms of structure, it appeared necessary to verify and extend the previous work with particular emphasis on divalent metals and the effect of alloying elements of different valence in dilute liquid solutions. The present work includes: 1—A determination of the resistivity of high purity liquid magnesium, tin, indium, copper, zinc, and cadmium as a function of temperature. 2—The effect of 1 atom pct of copper, cadmium, aluminum, tin, antimony, and

Jan 1, 1954

By T. D. Guldem, J. L. Kaae

ALLOYS with nominal composition of 45-Fe 35-Ni 20-Cr, ASTM-B-163, known under the commercial names of Incoloy 800 and Sanicro 31 (Alloy 800), are often employed at elevated temperatures for extended periods. Therefore, knowledge of the aging behavior of these alloys is of considerable importance. Significant decreases in ductility and increases in yield strength have been observed in the 45-Fe 35-Ni 20-Cr alloys containing about 0.4 pct Ti and 0.4 pct A1 after long-term aging at 540" to 700"~."~ However, no direct evidence has been presented for precipitation phenomena that might result in such changes. Strengthening effects have been attributed to the effects of local or-dering.3 Since y&apos; precipitation (Ni3A1, Ti) is known to occur in similar alloys which contain more titanium and aluminum,4-7 it was decided to explore the possibility that y&apos; might precipitate in these alloys and might be responsible for the changes in mechanical properties on aging. This note reports some observations of two distict types of matrix precipitates made by means of transmission electron microscopy, in a 45-Fe 35-Ni 20-Cr alloy containing 0.31 pct Ti and 0.4 pct Al. The steel used in this investigation was obtained from the Sand-vik Steel Works; it is designated Sanicro-31 (Alloy 800). The chemical composition of the alloy is given in Table I. Aging of solution-treated material at 700" and 800°C for 130 and 100 hr, respectively, produced the matrix precipitates shown in Figs. l(a) and l(b). It is apparent from these micrographs that the precipitate particles occurred in the form of thin square plates parallel to the matrix cube planes. Extraction replication and selected-area electron diffraction showed that the precipitates were M23C6. Coherency strains, consistent with the semicoherent nature of small M23C6 precipitates,&apos; were evident for certain imaging conditions. In addition to matrix precipitation, preferential precipitation of M23C6 on dislocations was common, as has been reported previously for austenitic stainless steels.&apos;" Specimens aged for longer times (-300 hr) at 700°C exhibited a different type of coherent matrix precipitate in addition to the M23C6. An example is shown in Figs. 2(a) and 2(b). In addition to the few large M23C6 precipitates, small precipitates exhibiting strain contrastl0,ll are present. The "line of no contrast" of the strain field of a given precipitate lies along differ-

Jan 1, 1970

By J. Murray Riddell

The method of treating hazards wherein value is decreased, is cited by R. D. Parks. Quite properly, the theory of probabilities is made use of when multiple hazards are under consideration. E. F. Fitzhugh, Jr. $ deals with the enhancement phase graphically and uses percentage of expectancy as derived by a study of conditions and the selection of a chance factor. It is believed that both of the authors referred to fully recognize the part which human judgment plays, and as coupled with experience, training, and the application of the theory of probabilities; in that respect the composer of this paper is in accord. Within the past year, the task of arriving at a mathematical method for handling the enhancement phase, and, additionally, coupling the negative and positive phases, was explored. In citing the hazard, or negative phase, reference is made to the text by Parks. Types of Items far Consideration On the hazard, or negative, side some of the common items to be considered are: 1. Subsidence and resulting damage. 2. Flo wage of water above that anticipated. 3. Geological. (a) Decline in quality of probable ore, and/or (b) Decline in quantity of probable ore. 4. Depressed economic conditions. 5. Litigation. Similarly, on the enhancement, or positive, side common items to be considered are: 1. Flo wage of water below that estimated. 2. Geological. (a) Increase in quality of probable ore, and/or (b) Increase in quantity of probable ore. 3. Elevated economic conditions. 4. Litigation. 5. Technological advance in the art. Tn all of the above items no consideration is given to placing a value on, or giving consideration to, possibilities. For example, referring to Table 1, the estimated normal present value (Vp) of a property, exclusive of risk consideration, is taken as $100,000. If subsidence affects the usefulness of the shaft, the present value of the property will decrease to $60,000, and it is judged that there is a 1 in 4 chance that the shaft will be impaired;, consequent.ly, if subsidence took place, the present value would be reduced ($100,000-$60,000) $40,000, but since the chance is 1 in 4, the allowable reduction would be only one-fourth of $40,000, or $10,000, or a discount of 10 pct (hazard factor) of the original value; the related safety factor is taken as unity minus 0.10, or 0.90. Thus, the original Vp, $100,000, multiplied by the safety factor ($100,000 X 0.90) gives $90,000, which is the adjusted present value of the property in this single instance. Additionally, there is a water hazard, which, if encountered, will reduce the present value to $85,000. The chance is 1 in 3. Following through with the same reasoning as shown above, the derived safety factor will be 0.95. To arrive at a single multiplying factor which will express the combined risks, the two safety factors are multiplied together, 0.90 X 0.95 = 0.855. That factor when multiplied by the origirial Vp will give the adjusted, and

Jan 1, 1950

By E. R. Buchanan, R. E. Reed-Hill

Cylindrical magnesium single crystals were deformed in torsion. The axis of torsion was the basal pole. Five crystals were deformed to different strains between 0.08 and 1.03 and then sectioned in order to determine their dislocation densities using the transmission electron microscope. The work hardening rate of all specimens was at least an order of magnitude higher than that normally associated with easy glide in a tension test and comparable to that obserzed in stage B of a tension test. The correspondence between stage B in a tension test and the initial stages of a torsion test is believed to result from the fact that in both cases deformation occurs in a structure containing roughly equivalent densities of the dislocations associated with the three basal slip vectors. THERE are three basic ways of changing the shape of a crystal using slip dislocations. The crystal can be sheared along a slip direction in a slip plane; it can be bent about an axis in the slip plane normal to the slip direction; and, if the slip plane contains multiple slip directions, it can be twisted or rotated about the slip plane normal. Of the three processes, generally known as translational, flexural, and rotational slip, only rotational slip has not been extensively investigated. The object of the present research was to obtain basic information about this phase of crystalline plasticity. This paper is concerned with some aspects of the stress-strain curves obtained by twisting magnesium crystals about their basal poles. Magnesium was selected for four reasons. One, its recovery rate at room temperature is relatively low. Two, single crystals may be easily grown. Three, at room temperature the critical resolved shear stress for basal slip is about two orders of magnitude lower than that for nonbasal slip, so that rotational slip might be expected to occur primarily by basal slip. Finally, relationships between flow stress, shear strain, and dislocation density have been determined for tensile deformation of magnesium crystals,&apos; thereby providing a basis of comparison for the torsional results. EXPERIMENTAL PROCEDURES Crystals were grown from 0.5 in. diam extruded sublimed magnesium rod furnished by the Dow Chemical Co. who reported that it contained in weight percent less than 0.0003 Al, 0.01 Ca, 0.01 Cu, 0.0012 Fe, 0.001 Mn, 0.0005 Ni, 0.003 Pb, 0.001 Si, 0.01 Sn, and 0.02 Zn, with the balance magnesium. All crystals were grown in a dried argon atmosphere using Jill-son&apos;s2 modified Bridgman technique. Two different methods were used to obtain crystals with the basal plane normal to the specimen axis. These included direct growth from seeds of the proper orientation, and spark machining (trepanning) of 0.5 in. diam cylinders from larger (1.5 in. diam) randomly grown crystals. The crystals thus produced were polished in a 20 pct HC1 water solution and then etched in a 1 pct HC1 water solution to develop etch pits lying in rows parallel to the basal plane trace. The crystals were then revolved about their axes on the stage of a low-powered microscope. Torsion specimens were prepared only from those crystals whose axes were normal to the rows of etch pits. It is estimated that this simple orientation method was accurate to about 51 deg. 1.625 in. long cylinders were next cut from these selected crystals and then acid machined in a 20 pct HC1 water solution into torsion specimens with a 1 in. long by 0.30 in. diam reduced gage section. Following this, they were annealed in air at 400°C and furnace cooled to room temperature. The specimens were given a final polish in a 10 pct HC1 water solution, rinsed in ethanol, dried, and cemented into brass grips with an epoxy resin. In addition to the torsion specimens, several tensile specimens with their basal planes at 45 deg to the stress axis were also prepared with similar dimensions except that the gage sections were increased to 4 in. in length. The torsion specimens were tested in the apparatus

Jan 1, 1970

By W. M. Weigel

Salt production in Louisiana and Texas at the present time is entirely from salt domes of the interior and coastal groups. Before and during the Civil War salt was recovered from numerous salines and salt springs by evaporation in open kettles. The location of these in nearly every instance was near what is now known to be a salt dome, and the source of the salt in the salines and spring waters was that in the salt core. The tops of many of the shallower domes have been subjected to erosion1. The discovery that the salt occurred as large masses of rock salt in the form of domes was made in May, 1802, at Avery Island, La., by John Marsh Avery, grandson of the original owner, John C. Marsh, who built the old salt works in 18122. The first shaft for mining was sunk on the Avery dome in 1867 by Chouteau and Price. It was 90 ft. deep, about 58 ft. being in solid salt. It was abandoned in 1870. There are three general groups or fields of salt domes; interior Louisiana in northern Louisiana, interior Texas in northeastern Texas, and the coastal domes nearer the Gulf Coast and extending from the Mississippi River to the Rio Grande. This last group contains by far the greatest number of domes. As many of the coastal domes especially are prolific producers of petroleum and a few of sulfur, their geology has been intensively studied and fully covered in the literature. The depth to the top of the salt varies from near the surface, where shallow ground waters have dissolved the salt to just below recent deposits, to several thousand feet, where the depth has been cstimated only by geophysical methods. The diameter of the salt core varies from less than 1/2 mile to over 2 miles. Only domes where the salt is comparatively near the surface have been developed for commercial salt. Three deeper domes, which will be described later, have recently been developed or are in process of development, as a source of brine for chemical use. Fig. 1 shows the location of the domes so far developed for commercial salt and brine. Nos. 1, 2, 4, 7, 8, 9 and 10 are in the Gulf Coastal field,

Jan 1, 1938

By W. M. Weigel

Salt production in Louisiana and Texas at the present time is entirely from salt domes of the interior and coastal groups. Before and during the Civil War salt was recovered from numerous salines and salt springs by evaporation in open kettles. The location of these in nearly every instance was near what is now known to be a salt dome, and the source of the salt in the salines and spring waters was that in the salt core. The tops of many of the shallower domes have been subjected to erosion1. The discovery that the salt occurred as large masses of rock salt in the form of domes was made in May, 1802, at Avery Island, La., by John Marsh Avery, grandson of the original owner, John C. Marsh, who built the old salt works in 18122. The first shaft for mining was sunk on the Avery dome in 1867 by Chouteau and Price. It was 90 ft. deep, about 58 ft. being in solid salt. It was abandoned in 1870. There are three general groups or fields of salt domes; interior Louisiana in northern Louisiana, interior Texas in northeastern Texas, and the coastal domes nearer the Gulf Coast and extending from the Mississippi River to the Rio Grande. This last group contains by far the greatest number of domes. As many of the coastal domes especially are prolific producers of petroleum and a few of sulfur, their geology has been intensively studied and fully covered in the literature. The depth to the top of the salt varies from near the surface, where shallow ground waters have dissolved the salt to just below recent deposits, to several thousand feet, where the depth has been cstimated only by geophysical methods. The diameter of the salt core varies from less than 1/2 mile to over 2 miles. Only domes where the salt is comparatively near the surface have been developed for commercial salt. Three deeper domes, which will be described later, have recently been developed or are in process of development, as a source of brine for chemical use. Fig. 1 shows the location of the domes so far developed for commercial salt and brine. Nos. 1, 2, 4, 7, 8, 9 and 10 are in the Gulf Coastal field,

Jan 1, 1938