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By John A. Gann

The following investigation constitutes a brief réumé of the more important binary magnesium alloys from the standpoint of metallo-graphic technique, and the effect of heat treatment on structure and properties. The comparative newness of the subject justifies this procedure as a preface to a more detailed study of each individual series of alloys. The work was started with the idea of practical application in the industry rather than as a theoretical investigation. The alloy compositions studied were selected as those most likely to show whether heat treatment would produce beneficial results. Furthermore, it was considered satisfactory to use commercial 99.9 per cent. magnesium, the best commercial grade of alloying ingredients, and to limit the time of heat treatment at the expense of incomplete equilibrium. These facts must be kept in mind when examining the results obtained, and the conclusions drawn. Preparation of Alloys All melts were made in an oil-fired cast-steel pot, approximately 12 in. dia, by 12 in. deep. Approximately 15 lb. of flux and 50 lb. of magnesium were melted and the calculated amount of alloying metal was added. After thorough alloying and puddling, the metal was chill cast in a graphite mold with four 1/2 by 1/2 by 4 in. bars fed from a common sprue and runner. The next higher composition alloy in a given series was made by adding the calculated amount of metal to the heel from the preceding cast. The pot was thoroughly cleaned after each series and new flux then introduced, thus avoiding possible contamination from earlier melts. The percentage compositions given in Table 1 are the calculated values. While not all alloys were analyzed, enough were checked to indicate that the reported compositions are correct to a few tenths of one per cent. A more detailed description of the foundry methods employed has been given in a previous paper. 1

Jan 1, 1929

By John A. Gann

The following investigation constitutes a brief réumé of the more important binary magnesium alloys from the standpoint of metallo-graphic technique, and the effect of heat treatment on structure and properties. The comparative newness of the subject justifies this procedure as a preface to a more detailed study of each individual series of alloys. The work was started with the idea of practical application in the industry rather than as a theoretical investigation. The alloy compositions studied were selected as those most likely to show whether heat treatment would produce beneficial results. Furthermore, it was considered satisfactory to use commercial 99.9 per cent. magnesium, the best commercial grade of alloying ingredients, and to limit the time of heat treatment at the expense of incomplete equilibrium. These facts must be kept in mind when examining the results obtained, and the conclusions drawn. Preparation of Alloys All melts were made in an oil-fired cast-steel pot, approximately 12 in. dia, by 12 in. deep. Approximately 15 lb. of flux and 50 lb. of magnesium were melted and the calculated amount of alloying metal was added. After thorough alloying and puddling, the metal was chill cast in a graphite mold with four 1/2 by 1/2 by 4 in. bars fed from a common sprue and runner. The next higher composition alloy in a given series was made by adding the calculated amount of metal to the heel from the preceding cast. The pot was thoroughly cleaned after each series and new flux then introduced, thus avoiding possible contamination from earlier melts. The percentage compositions given in Table 1 are the calculated values. While not all alloys were analyzed, enough were checked to indicate that the reported compositions are correct to a few tenths of one per cent. A more detailed description of the foundry methods employed has been given in a previous paper. 1

Jan 1, 1929

ENGINEERS AVAILABLE (Under this heading will be published notes sent to the Secretary of the Institute by members or other persons introduced by members.) Member, technical graduate, aged 36. Experienced copper metallurgist and mining geologist. Familiar also, through 15 years' broad practical experience, with mining, cyanidation, concentration (including oil flotation), metallurgical accounting, and mine and plant management. Best references. No. 237. Member, graduate engineer with 10 years' experience in malleable, gray -Iron, and steel, as chemist., metallographist, and metallurgist. Researches and investigations by laboratory methods and under works conditions. No objection to some routine. No. 243. Member, technical graduate, broad experience in coal, oil, and clay. Will go anywhere as mining geologist after Sept. 1, 1915. No. 244. Member, technical graduate, aged 30, married, with over 10 years' experience as chemist, engineer on construction, superintendent and general superintendent of bituminous coal and coke plants. SpeaksSpanish. References. No. 245. Member, open for engagement as mine safety inspector or as superintendent of bituminous coal mine. No. 246. Member, graduate mining engineer, with five years' experience in coal mining as mining engineer, construction engineer, pit boss, and superintendent, open for engagement. Best references. No. 247.

Jan 9, 1915

By O. W. Ellis

The question of the influence of gases upon the properties of copper has received the attention of a number of investigators, among whom Sieverts,' Iwase,2 Lobley and Jepson3 stand preeminent. Solubility of Gases in Copper Sieverts and Iwasé concerned themselves with the solubility of a variety of gases in the metal in the solid and liquid states. They determined the absorption coefficients of these gases and in all cases found a sharp change in solubility at the melting point of the metal. In this respect they disagree with Lobley and Jepson, who have based their opinions upon the appearance of small ingots of the metal which had been fused in an atmosphere of one or other of three gases and had then been rapidly cooled, while surrounded by gas, to the freezing point (rate—possibly 30" to 60" C. per sec.). The ingots that had been fused and cooled under nitrogen and carbon monoxide were free from blowholes and it was assumed that these gases were not absorbed in amounts much in excess of those which would dissolve in the solid metal; the ingots similarly treated under hydrogen were full of blowholes and it was assumed in this case that gas was ejected on solidification of the copper. The effect of varying the rate of freezing upon the character of the test ingots was not examined by these investigators; otherwise, it is felt, their views might have been subject to modification. Sieverts' most important contribution is that the solubility of a gas in any metal is proportional to the square root of its pressure or concentration. Knowing then the absorption coefficients of the various gases in copper, it should be possible to determine the analysis of the

Jan 1, 1929

By O. W. Ellis

The question of the influence of gases upon the properties of copper has received the attention of a number of investigators, among whom Sieverts,' Iwase,2 Lobley and Jepson3 stand preeminent. Solubility of Gases in Copper Sieverts and Iwasé concerned themselves with the solubility of a variety of gases in the metal in the solid and liquid states. They determined the absorption coefficients of these gases and in all cases found a sharp change in solubility at the melting point of the metal. In this respect they disagree with Lobley and Jepson, who have based their opinions upon the appearance of small ingots of the metal which had been fused in an atmosphere of one or other of three gases and had then been rapidly cooled, while surrounded by gas, to the freezing point (rate—possibly 30" to 60" C. per sec.). The ingots that had been fused and cooled under nitrogen and carbon monoxide were free from blowholes and it was assumed that these gases were not absorbed in amounts much in excess of those which would dissolve in the solid metal; the ingots similarly treated under hydrogen were full of blowholes and it was assumed in this case that gas was ejected on solidification of the copper. The effect of varying the rate of freezing upon the character of the test ingots was not examined by these investigators; otherwise, it is felt, their views might have been subject to modification. Sieverts' most important contribution is that the solubility of a gas in any metal is proportional to the square root of its pressure or concentration. Knowing then the absorption coefficients of the various gases in copper, it should be possible to determine the analysis of the

Jan 1, 1929

Jan 7, 1976

1. How Does One Determine Whether an Ore Body Will Block-cave? Page Mark A. Smith......... 122 Harry A. Leidich........ 122 McHenry Mosier ...,.. 22 R. W. Hughes ........ 122 Sherman R. Burdick ....... 123 R. T. Gallagher........I 23 Benjamin F. Tillson...... 123 Lucien Eaton...........123 C. F. Jackson..... . .. 123 Philip B. Bucky........... 126 2. How Does One Determine the Block Dimensions and the Development Work Necessary to Make an Ore Body Cave? Mark A. Smith... 125, 127, 129 Harry A. Leidich..........126 McHenry Mosier......126, 127, 132 R. W. Hughes...........126 Sherman R. Burdick.........127 R. T. Gallagher...........127 Benjamin F. Tillson......127,131 L. E. Young............127 Robert D. Hoffman.......128, 132 Gerald Sherman..........128 Philip B. Bucky......130, 131, 132 K. S. McClellan..........132 Tell Ertl.............132 3. How Do the Forces Act and What Are the Stresses Developed in a Block That Cause It to Block-cave? Mark A. Smith.........132, 135 Harry A. Leidich........133 McHenry Mosier . .. 133 R. W. Hughes ....... 133 Sherman R. Burdick..... . 133 R. T. Gallagher..........134 C. F. . Price, Jr. ........134 Benjamin F. Tillson.........134 C. F. Jackson......134, 135,137 R. Taborelli...........135 Frank A. Ayer ... .....136 Philip B. Bucky . .........136 Rollin Farmin . . .......136 . . . Weysser.....135, 136, 137 George S. Rice...........137 4. What Determines the Procedure in Removing Caved Ore? Harry A Leidich...........137 McHenry Mosier........137,141 R. W. Hughes...........137 Sherman R. Burdick........138 R. T. Gallagher...........138 Mark . Smith...........138 Philip B. Bucky......140,141,143 C. F. B. Price, Jr..........140 R. H. Bennett...........141 C. F. Jackson..........141, 143 Gerald Sherman..........141 Tell Ertl.............141 .. .. ..................143 C. H. Shoemaker..........143 5. What Are the Criteria for Determining the Efficiency of a Block-caving Operation? Harry A. Leidich.......... 143 McHenry Mosier......... 144 R. W. Hughes........... 144 Sherman R. Burdick.......144 R. T. Gallagher . ......... 144

Jan 1, 1946

By W. E. C. Coxe

At the meeting of the Institute in Philadelphia, in June, 1876, it was my pleasure to read a paper on the "Manufacture and Endurance of Iron Rails." I then spoke of some trial rails which had been placed in the down track of the Philadelphia and Reading Railroad, over which passed, in addition to merchandise and passengers, most of the heavy coal traffic of that company. One of these rails, made at the Philadelphia and Reading Rolling Mill in 1870, and then placed in the track, was removed in 1876, after having carried about 55,000,000 gross tons, and was on exhibition at the Centennial Exhibition. A piece of this worn rail, twisted cold, was also shown there. One of the same series of rails was allowed to remain in the track until 1878, and short sections of this rail, as well as one not worn, to show its original shape, are presented for your inspection. A comparison of the two will show that the top of the head or tread has morn down 3/16ths of an inch during its nine years of service. It carried in that time 67,000,000 gross tons of freight, passengers, cars, and engines. This rail was made in the usual way of manufacturing iron rails at the Philadelphia and Reading Rolling Mill. The head was made from puddled iron bars, piled, heated, and rolled into bars, 41/2 and 3 inches wide by 1 inch thick, these bars, breaking joints, were made into a pile in section 9 inches square, heated and rolled into slabs 9 inches wide and 2 inches thick; the balance of the rail-pile was made of 41/2 and 3-inch bars, rolled from two-thirds old rails and one-third puddled iron, the

Jan 1, 1880

By J. B. Coher, M. B. Bever

COLD work destroys long-range order, as was first observed by Dehlinger and Graf.1 Dahl2 showed that the mechanical disordering caused by cold work produces changes in those properties that are affected by long-range order. The existence of order has a marked effect on tile manner in which an alloy deforms and therefore on its mechanical properties.L' The relation between order and deformation behavior however, is only beginning to be understood. Seemann and G1ander4 suggested that cold work reduces an ordered alloy to a kind of gruel of antiphase domains. According to Cottrell,5 superdis-locations and pairs of dislocations in a slip plane connected by a strip of anti-phase domain boundary provide deformation mechanisms which do not change the state of order. In general, however, slip may be expected to produce new domain boundaries and destroy order if dislocations move on intersecting planes or cut through existing domain boundaries. The yield strength of an ordered alloy may pass through a maximum with decreasing domain size.5"7 The reduction of domain size resulting from cold work may, therefore, lead to a maximum in strength properties. Flinn8 suggests that dislocations can climb by short-range diffusion during deformation and thus can generate domain boundaries not only on slip planes, but also on other planes which will be those with the lowest domain-boundary energy. It has long been known that the rate of strain hardening of an alloy in the ordered state is larger than in the disordered state.3'9 Also the slip bands in ordered CU3, AU10 and Ni3Mn" are finer than in the disordered alloys. The stress which causes initial yielding in Cu,Au passes through a maximum with decreasing domain size.6'12 A maximum has also been observed in the hardness of ordered Ni3Mn as a function of strain.' These observations suggest, but do not prove, that domain size reduction occurs during deformation. According to Fisher13 slip destroys short-range order and thus the strength of an alloy is related to the degree of short-range order present. Rudman and Averbach14 and Averbach et a1.,15 demonstrated that cold work reduces short-range order in copper-gold and gold-silver alloys. Destruction of long-range and short-range order by cold work implies slip on an appreciable fraction of planes. Yielding of an alloy in which short-range order exists or antiphase domain boundaries are present should be discontinuous because the first dislocations moving across the slip plane meet with the largest resistance.5 Such discontinuous yielding has been observed in CU3AU6,16 and Cuzn.l7 This phenomenon, however, can also be explained by mechanisms not involving order.b The published investigations of the effects of cold work on alloys with long-range or short-range order have not been covered thoroughly in reviews of order-disorder phenomena. These investigations, therefore, will be listed here. They have been concerned with strength properties> 2,3,6,8,9,12,16-21 electrical resistivity,2,4,18,19,21-26: thermoelectric power, magnetic properties,2,18,21,26 and X-ray strain'1,2,14,15,27,28 The slip systems and the appearance of the microstructure after deformation in ordered and disordered alloys have also been investigated. 6.10.ll,l7,23,29,30 The alloys used in these investigations were copper-gold. 1-4,6,9,10,14,16,18 23-26,28,29 copper-zinc. L7. 19. 20,30 nickel-manganese,2 11,21 iron-aluminum. iron-nickel,' copper palladium,4,18,22 gold-silver.4,18,22 and palladium-silver-copper.4 In the work reported here. the changes in properties of polycrystalline Cu3Au were investigated as functions of strain in wire drawing and rolling. Specimens were heat treated before deformation

Jan 1, 1961

By J. C. Branner

DuriKg the past two or three years I have seen statements regarding the first discovery of fullers' earth in this country that seem to require correction or modification. One appears again in the Mineral Resources of the United States for 1909, part II., p. 738, where it is said that 'fullers' earth was firat discovered in the United States at Quincy, Fla., in 1893." In this connection the following bit of unpublished history concerning fullers' earth in the State of Arkansas is worthy of attention. In April, 1891, when I was State Geologist of Arkansas, a Swede named John Olsen, formerly a copper-miner in Michigan, but then living south of Little Rock, brought me a sample of what he thought mas fullers' earth. He reported that it was from near the town of Alexander, the locality being 1 S. 13 W., section 8, SW. quarter of the SE. quarter. My chemist, Dr. R. N. Brackett, analyzed the material, and reported: Per Cent. Silica,.....SiO2 .... 63.19 Alumina,.... A12O3 .... 18.76 Iron,.....Fe2O3 .... 7.05 Lime,.,...CaO .... 0.78 Magnesia,.... MgO .... 1.68 Potash,.... K2O ,... 0.21 Soda,.....Na2O .... 1.50 Loss on ignition,........7.57 100.74 Water at 110° to 115° C. = 7.84. Another sample from about the same locality, also brought by John Olsen, on analysis by Dr. Brackett gave :

Jan 1, 1913

By F. R. Wadleigh

There are in commercial use today in the United States various classifications of coal, each based on one or more characteristics. The bases of these classifications may be described as follows: GeNeRaL Basis Examples 1. Geological By seams and basins (local). 2. Chemical By constituents, as determined by analysis—ash, volatilc, slilfur and hcating value. 3. Combustion Characteristics As frce-burning, smokeless, character of ash. 4. Carbonization Characteristics Coking, noncoking. 5. Physical Characteristics Splint, soft, hard, block. 6. Geographical States, Fields, Counties, Districts. 7. Sizes By dimension or name. 8. Company Names Producing or sales company names, as "C. C. B. Pocahontas," etc. 9. Trade Names, copyrighted or not 10. Uses Gas, steam, coking, locomotive, fuel, bunkers, etc. 11. Use Methods Stoker coal. 12. Pools (Tidewater Exchanges) Analyses Size Seams Railroads Uses Structure Districts There are also classifications founded on more than one basis, as follows: 1. Geographical and Geological. By locality of mines (State, District, County) and seam. Examples: Cambria County, Miller Seam, New River, Sewell Seam. 2. Geographical and Chemical. Alabama medium volatile. 3. Combustion Characteristics and Ash Content. Free-burning, red ash (anthra- cite). 4. Carbonization Characteristics and Analysis. Noncoking, high-volatile, low sulfur. 5. Physical and Carbonization Characteristics. Splint, noncoking. 6. Size and Use. ¾-in. gas coal; domestic sizes (prepared sizcs); stcam sizcs. 7. Company Name and Seam. Consolidation Co., Elkhorn. 8. Size and Analysis. Low-volatile run-of-mine; low-volatilc slack. 9. Sizes—size of screen and name. 6 by sin. lump. 10. Chemical and USP. High-volatile steam. 11. Geographical and Use. Youghiogheny gas. 12. District, Size and Use. Pittsburgh gas l¼-in. lump. ,

Jan 1, 1930

All the TECHNICAL PUBLICATIONS and CONTRIBUTIONS published in 1933 are available at Institute headquarters, unless otherwise noted. They are also on file in many public, university and technical libraries and, when so indicated in the list, may be found in the TRANSACTIONS. Copies of the TECHNICAL PUBLICATIONS have been mailed to those members of the Institute who are registered in the different classes: A-Metal Mining; B-Milling and Concentration; C-Iron and Steel Division; D-Nonferrous Metallurgy;. E-Insti¬ tute of Metals Division; F-Coal Division; G-Petroleum Division; H-Nonmetallic Minerals; I-Mining Geology; J-Mineral Industry Education Division; K-Mining Administration; L-Geophysical Prospecting. Other members may obtain copies by writing to the Secretary. Copies of CONTRIBUTIONS may also be obtained from the Secretary's office. Additional copies are sold at the rate of 1 cent per page; minimum charge, 25 cents. Nonmembers may purchase the papers at the prices mentioned. METAL MINING TECH- NICAL PUBLI- TITLE AUTHOR MEETING TRANS. CATION VOLUME No. AND PAGE* 499-A.47 Red Ore Mines of the Woodward T. C. DeSollar New York, Iron Company at Bessemer, Feb., 1933 Alabama (11) CONTRI¬ BUTION No. 1-A The Owyhee Tunnels (16) P. R. Hines New York, Feb., 1933 2-A Sinking and Equipment of the No. D. D. Homer New York, 2 Shaft at Minas de Mata- R. H. Cromwell Feb., 1933 hambre (25) 3-A Subsidence Resulting from the Charles W. Allen New York, Athens System of Mining at Feb., 1933 Negaunee, Michigan (8) 4-A Effect of Approximately Vertical P. B. Bucky New York, Cracks on the Behavior of Hori- Feb., 1933 zontally. Lying Roof Strata (16) 21-A Selection of a Mining System (11) R. K. Warner New York, Feb., 1933

Jan 1, 1933

By J. D. Mooney, D. L. Darnell

The accompanying chart has been drawn for the convenicncc of engineers as' a means of quickly determining the correct number of plies of conveyor belts operating under specific conditions. The calculations are based on the average safe strength (factor of safety, 15) of the various standard rubber conveyor belts. The calculations assume maximum loading conditions; that is, the belt is considered as carrying the greatest load that it will handle without spillage at ordinary belt speeds. This not only produces the most economical operating conditions, but also the maximum tension in the belt. The chart is a graphical representation of the formula: Where, p = kg W(L + 10H) p = the correct number of plies k = a constant, depending on the type of drive g = the weight 'in pounds per cubic foot of material handled W = the width of the belt in inches L = the length of the belt in feet (approximately twice the center distance). H = the difference in elevation between the head and tail pulleys, in feet. For a simple drive, with a bare pulley, k = ----1 For a simple drive, with a rubber-lagged pulley, k = --- 1 For a, tandem drivej with bare pulleys, k = 1/375.000 For a tandem drive, with rubber-lagged pulleys, k = ---1 The chart is drawn for a simple drive, with a bare pulley (k — =e)1 ; therefore, the number of plies obtained from the chart should be multi- ' plied by the factor 0.83 or 5/6 for simple, lagged drive; the factor 0.67 or 2/3 for tandem, bare; and the factor 0.55 or 11/20, for tandem, lagged. The formula p = kgW(L + 10H) has been developed mathematically

Jan 1, 1916

THE opening session of the Institute was held at the rooms of the American Society of Civil Engineers, No. 4 East 23d Street, Vice-President R. W. Raymond in the chair. After a short introductory address by the chairman, the following names were presented by the Council for election as members and associates of the Institute. They were unanimously elected : MEMBERS. Abbott, James W., - Lake City, Col. Abbott, J. J., Jr., - Lake City, Col. Bartlett, J. C., - Cambridge, Mass. Billings, G. H., - Boston, Mass. Blake, Frank C., - Lafayette College, Easton, Pa. Dewey, Fred. P., - Lafayette College, Easton, Pa. Douglass, Samuel T., - Ann Arbor, Mich. Emmons, S. F., - New York City. Engle, George U., - Philadelphia. Harrington, Dr. Bernard J., - Montreal, Canada. Hayden, Wm. B., - Columbus, O. Hill, Leslie C., - Capelton, Quebec, Canada. Land, W. J., - Atlanta, Ga. May, Wm. A., - Scranton, Pa. Mills, James E., - St. Louis, Mo. Moore, Charles W., - Montezuma, Ind. Page, William Byrd, - Lexington, Ky. Putnam, Douglas, Jr., - Ashland, Ky. Richards, Henry, - Dover, N. J. Roberts, Percival, Jr., - Philadelphia. Sackett, S. G., - Brooklyn, N. Y. Schley, Wm. S., - Atlanta, Ga. Setz, Gustav, - Mine La Motte, Mo. Talbutt, John H., - Lexington, Ky. Torrey, Herbert G., - U. S. Assay Office, New York City. Wernlitz, Fred. W., - Cartersville, Bartow Co., Ga. Wiestling, Geo. B., - Mont Alto, Franklin Co., Pa.

Jan 1, 1877

By B. G. Bunting, D. L. Abata, J. Robb, J. H. Johnson

Toxic gases produced by the detonation of six explosives were measured in an underground hardrock metal mine during mining operations. The explosives included two semi-gelatin dynamites, three slurry explosives, and an ammonium nitrate, fuel-oil/ammonia dynamite combination. Explosives were detonated at the face of a drift and toxic gases produced by the detonation were trapped at the end of the drift by a bulkhead located a short distance away from the face. Toxic gas concentrations were then measured with direct readout instruments and together with the containment volume, the toxic gas volumes per mass of explosive were calculated. Toxic gas measurements were found in the following ranges (ft3/1bm): NO, 0.0100-0.035; N02, 0.003-0.019; CO, 0.08-0.30; SO2, 0.00-0.05; and CO2, 0.7-1.8. Results showed that toxic gas production (ft3/lbm) correlated with the densities (kg/m3) and energy densities (kJ/kg) of the explosives tested.

Jan 1, 1983

By H. B. Pulsifer

This paper outlines a method for rapid production of flat,, granular surfaces on many of the medium hard alloys. Grinding wheels and fabrics on wheels are not used; the purpose is accomplished by rubbing on emery papers and on fine abrasives heaped on hand boards. The advantages of chromic acid in the solutions for etching nickel and copper alloys are explained. Steels may require an additional step in the mechanical smoothing owing to the lack of an ideal etchant. Chloric acid is a rapid etchant for steel. Thirty-six photomicrographs illustrate the steps in smoothing and the clearness with which structures can be rapidly exposed. New structures in low-carbon steels are announced. After a little practice, many materials can be finished within two or three minutes. CUPRONICKELS In the previous papers on the metallography of copper and magnesiurn which the author has presented to this Institute there has been an attempt to demonstrate the advantages of minimizing the mechanical work of surfacing and depending more on chemical means; the present paper continues the research into a still wider field. It is obvious that the success of a chemical method for smoothing and etching depends almost entirely on the use of a suitable reagent. The etchant must remove the surface granulations and outline the structures. A very special type of reaction between reagent and metal must be displayed. Promiscuous corrosion or the intensification of the attack about local couples formed by impurities or components must not be in evidence. There are several reagents that etch highly polished nickel and copper alloys very well. Acidified ferric chloride solutions, concentrated and dilute nitric acid solutions, and nitric and acetic acids in acetone have been used to good advantage for the purpose. However, if they are expected to etch rather deeply—that is, smooth as well as characterize— the results may be far from satisfactory. Advantages of Chromic Acid In a protracted series of experiments it has been found that the addit,ion of chromic acid may be of the most surprising benefit. The function

Jan 1, 1929

By H. B. Pulsifer

This paper outlines a method for rapid production of flat,, granular surfaces on many of the medium hard alloys. Grinding wheels and fabrics on wheels are not used; the purpose is accomplished by rubbing on emery papers and on fine abrasives heaped on hand boards. The advantages of chromic acid in the solutions for etching nickel and copper alloys are explained. Steels may require an additional step in the mechanical smoothing owing to the lack of an ideal etchant. Chloric acid is a rapid etchant for steel. Thirty-six photomicrographs illustrate the steps in smoothing and the clearness with which structures can be rapidly exposed. New structures in low-carbon steels are announced. After a little practice, many materials can be finished within two or three minutes. CUPRONICKELS In the previous papers on the metallography of copper and magnesiurn which the author has presented to this Institute there has been an attempt to demonstrate the advantages of minimizing the mechanical work of surfacing and depending more on chemical means; the present paper continues the research into a still wider field. It is obvious that the success of a chemical method for smoothing and etching depends almost entirely on the use of a suitable reagent. The etchant must remove the surface granulations and outline the structures. A very special type of reaction between reagent and metal must be displayed. Promiscuous corrosion or the intensification of the attack about local couples formed by impurities or components must not be in evidence. There are several reagents that etch highly polished nickel and copper alloys very well. Acidified ferric chloride solutions, concentrated and dilute nitric acid solutions, and nitric and acetic acids in acetone have been used to good advantage for the purpose. However, if they are expected to etch rather deeply—that is, smooth as well as characterize— the results may be far from satisfactory. Advantages of Chromic Acid In a protracted series of experiments it has been found that the addit,ion of chromic acid may be of the most surprising benefit. The function

Jan 1, 1929

Members whose deaths were reported from Apr 7, 1923, to Apr 5, 1924 Elected Died 1918 ADKINSON, HENRY M 1923 1900 AGNEW, WILLIAM C 1923 1894 ASHLEY, H H 1923 1897 AUSTIN, KENNETH 1924 1903 AYERS, EMMA L C 1923 1913 BAECHTOLD, CHARLES A 1924 1900 BAIN, HUGH A 1924 1919 BASHORE, E GORGAS 1923 1920 BATTELLE, GORDON 1923 1923 BAYLES, GERARD L 1924 1881 BROCK, CHARLES 1923 1903 BROOKE, HENRY 1923 1876 BROWN, HARVEY H 1923 1904 BROWN, THOMAS E 1923 1919 BUCK, DANIEL M 1924 1906 CHALMERS, THOMAS S 1924 1881 CLEMES, JOHN H 1923 1896 COLLINS, HENRY F 1924 1871 COURTIS, WILLIAM M 1923 1915 CRESSON, B F, JR 1923 1921 CROWE, WALDO P 1923 1920 DARNELL, J ORA 1923 1911 DAVIS, HENRY G 1924 1918 DAVIS, ROBERT S 1923 1916 DEANE, WILLARD A 1924 1901 DEMPSTER, WILLIAM 1924 1911 DEVEREUX, W B, JR 1923 1895 DICKENSON, F M 1924 1904 DRUM, FRANK G 1924 1875 DUDLEY, P H 1924 1916 EATON, ARTHUR 1923 1919 EATON,SHERMAN 1924 1911 GRIFFITH, WILLIAM 1924 1919 HILSDALE, PAUL 1923 1922 HODGES, I F 1923 1916 HOFIUS, MAX, T 1924 1914 HUGHES, HOWARD R 1924 1919 HUMMEL, CARL B 1923 1874 HUNT, ROBERT W 1923 1921 JONES, ERNEST EVANS 1923 1917 JOSLIN, CHARLES T 1923 1918 KASJENS, JACOB G 1923 1899 KIRKEGAARD, PETER 1924 1920 KLAUS, HARRY C 1923 1892 KNOERTZER, HENRI1924

Jan 1, 1923

By J. C. Bierlein, R. A. Dodd

Endurance strengths at 10' cycles, fatigue-hardening rates, and endurance strength/0.2 pct proof stress ratios have been determined jbr a range of Cu(Ni), Cu(Si), and S.R.0. Cu(Au) solid solutions. Some douht is cast on simple cross slip models of fatigue hardening in view of opposite composition dependencies of hardening displayed by Cu(Si) and Cu(Au). The temperature dependencies of hardening also are the opposite of predictions made on the basis of a cross slip model. A correlation apparently exists between the fatigue strength/0.2 Pc~ proof s1.re.s~ ratios and rates of fatigue hardening. An increase in PS/PS due to alloying or temperature change is accompanied by a decrease in hardening rate, and vice versa. In recent years there has been much interest in the determination of the dislocation structure of fatigued metals and alloys. The accumulated evidence, e.g., Refs. 1 to 5, suggests that the structure may be dependent on the stacking fault energy, 7, of the fatigued metal in the same way that fatigue hardening rates have also been shown to apparently depend on u .6' 7 The above research followed the various earlier theories relating crack nucleation to ease of cross slip, e.g., Refs. 8 to 131 so "ggesting that y may indeed be the parameter of principal significance in all facets of the fatigue process. However, comparatively little attention has been paid to correlating engineering fatigue data with observations of the above type. Certainly, it would be useful if potential engineering fatigue performance could be assessed from a knowledge of easily determined alloy properties, and the present research originated from this standpoint. TO investigate the widest Possible range of 7 would require the use of two solvent bases, e.g., aluminum and copper, but a reasonable coverage can be provided by copper-based solutions alone. Therefore, it was decided to work with Cu(Ni) and Cu(Si) solid solutions, the approximate stackillg fault energies of which are given in Table I. The y range extends from low, Cu(7.5 at- Pet Si), to moderately high in Cu(2-5 at. ~ct ~i) and two of the Cu(Ni) alloys. The values listed in Table I should be regarded as qualitative only, being derived as follows. Dillamore and smallman14 quote a value of 85 i 30 erg.cm-2 for the stacking fault energy of pure copper, based on an earlier value due to Howie and swannl5 corrected by Brown's formula.'' Since the ratios (alloy)h(pure copper) have been reported17,18 for Cu(Ni) alloys containing up to 30 pct Ni, approximate ) values for these alloys can be computed, and a rough estimate of 7 for Cu(50 at. pct Ni) obtained by extrapolation. The relatively low y value obtained in this way for Cu(50 at. pct Ni) coincides with the observation of Nakajima19 that the stacking fault probability is a maximum at this composition. Likewise, the y values for the three ~u(~i) alloys are estimates based on values given by Swann and Nuttingo corrected on the basis Of Brown's estimate that the true 7 values are probably 2.3 times greater than those originally computed. In addition to the above alloys it was decided to investigate short-range ordered (s.R.O.) CU(AU) alloys containing up to 25 at. pct Au. This last alloy has been shown to have a well-defined planar arrangement of dislocations when deformed,21,22 probably due to cross slip being restricted by the S.R.O. Engineering fatigue data was to be represented by the determination of endurance strengths, and these were to be correlated with fatigue hardening and mechanical property data. EXPERIMENTAL I, order to study the desired properties and property changes, the following alloys were prepared: Cu(2.5 at. pct Si), Cu(5.0 at. pct Si), Cu(7.5 at. pct Si), Cu(5.0 at. pct Ni), Cu(25.0 at. pct Nil, Cu(50.0 at. pct Ni), Cu(5.0 at. pct AU), Cu(15.0 at. pct AU), Cu(25.0 at. pct AU). The copper and gold were zone-refined, while the silicon was semiconductor grade. The nickel was of 99.95 p,t. purity.* All alloys were induction-melted in a *Kindly supplied by the International Nickel co. helium atmosphere, appropriate precautions being taken to avoid segregation in the Cu-Au series. Rod stock was obtained by rolling and swag,ng. A few Bridgman single crystals were grown for fatigue-hardening studies, but most material was machined into polycrystalline fatigue speciments of the design shown in Fig. 1, and into polycrystalline tensile and fatigue-hardening specimens of simple cylindrical design. All specimens except Cu(Au) were annealed; the latter were quenched from above T, to produce short-range order. A few of the quenched alloys were examined for long-range order by step-scanning over

Jan 1, 1969