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By A. C. Fieldner

In November, 1926, the American Engineering Standards Committee (now the American Standards Association) called a meeting of representatives of various professional societies and industrial, educational and governmental organizations to consider what action, if any, should be taken on the classification of North American coals. This meeting was called because a system for the use classification of coal, proposed by George H. Ashley, had been referred to the committee by the Coal Mining Institute of America. This meeting, at Pittsburgh, was well attended and was definitely in favor of taking up the whole question of scientific and use classification of coals, including all the various ranks from lignite to anthracite. The American Society for Testing Materials was recommended as the sponsor organization to take charge of the work and organize the sectional committee according to the rules of the American Standards Association. The American Society for Testing Materials proceeded with the organization of the sectional committee, holding a meeting in Philadelphia, June 10, 1927. Officers were elected, regulations adopted, and general plans for carrying out the work were outlined. The total membership of 28 comprising the sectional committee consists of 8 producers, 2 distributors, 9 consumers and 9 members representing general and scientific interest. From this committee three technical committees of 10 to 12 members each were organized: Scientific Classification, H. J. Rose, chairman; Use Classification, W. H. Fulweiler, chairman; Marketing Practice, F. R. Wadleigh, chairman. The Technical Committee on Scientific Classification was requested to formulate a system of coal classification based on chemical and physical properties of coal and with reference to origin and constitution. The Technical Committee on Use Classification was charged with developing a system of classification, if possible, based primarily on the uses of coal and commercial practice; this system to be correlated with the scientific system as far as possible and desirable. The Technical Commitlee on Marketing Practice was formed to collect and collate information on commercial practice for the benefit of the other two committees. The first meetings of the technical committees were held on Nov. 17, 1927, and the first informal progress reports were submitted to the

Jan 1, 1930

By Klaus Schwerdtfeger

Activities of lead in Pt-Pb and Pd-Pb melts in the temperature range of 800° to 1200°C have been detev-mined from electromotive-. force measurements 202th the cells Both systems display strong negative deviations from Raoult's law. The data obtained with cell [1] were combined with available data on the activity of PbO in silica-satuvaterl PbO-SbO2 melts to calculate the standard free cnergy of formation 01- liquid PbO. FREE energies of formation of oxides and activities of components in metal and oxide melts can be determined with galvanic cells consisting of a metal phase, an electrolyte containing the oxide of one of the components of the metal phase, and an oxygen electrode. This technique has been used previously to measure the standard free energy of formation of solid sio2, 1 and activities in Fe-si, CO-si,2 Ni-Si,2 and CaO-P2O5 3 melts. The present paper reports activities in Pt-Pb and Pd-Pb melts as measured with the same experimental technique. EXPERIMENTAL METHOD General Considerations. The following cells were used: Pbl (PbO-SiO2)liquid, SiO2 Pt-Pb 1 (PbO-SiOz)liquid, SiO2solidO2 [2] Pd-Pb (PbO-SiOz)liquid, SiO2solid O2 [3] Liquid alloy and' oxide melt were contained together in a silica glass crucible of essentially the same design as described previously.1'2 The PbO-SiO2 melts are ionic conductors.' During the experiment, the silica glass crystalizes in a layer adjacent to the electrolyte. The electrolyte equilibrates with solid silica and hence attains the composition of the Si02-liquidus curve in the system PbO-SiO2 at any particular temperature. Molybdenum wires were used to establish contact with the liquid metal. The oxygen electrode, which reaches the surface of the PbO-SiO, electrolyte from above, consists of a platinum wire inserted into a ceramic tube and provided with a 2-mm-diam platinum bead at its end. Gas of known oxygen partial pressure (pure oxygen of 1 atm: air, or N2 with 1.04 pct 0,) is blown through the ceramic tube onto the surface of the electrolyte. The cell reaction is Pb (metal) + 1/2O2 (gas) = PbO (electrolyte) [4] No oxidation of platinum or palladium ("displacement reaction") occurs. This is to be expected from the noble character of platinum and palladium, but was also shown experimentally, as described in the next section. The galvanic electromotive force of the cell is given by where AG is the change in free energy for Reaction [4], E(=2) is the number of electrical equivalents necessary to form 1 mole of PbO, and F is the Faraday constant. Formula [5] is valid only if no junction potential exists within the electrolyte. Junction potentials occur only when the compositions of the electrolyte are markedly different at the electrodes. Such differences are negligible in the PbO-SiO, electrolyte, as shown in the next section. Since molybdenum contact leads are used, appropriate corrections were made on the measured electromotive forces to account for the thermoelectric effect of the Mo-Pt couple. The thermoelec-tromotive forces were measured separately with a Mo-Pt couple, and were found to vary linearly from 19 mv at 740°C to 40 mv at 1310°C with molybdenum being positive and platinum negative (cold junction at 25°C). Extrapolation of these values to higher temperatures yields values which are in satisfactory agreement with those obtained previously in the temperature range 1440° to 1630°c.1,2 The change in free energy for Reaction [4] is expressed as where chemical potentials of the species. The value of constant for a given temperature because the slag composition is fixed. Inserting [6] into [5] and using appropriate expressions for upb and uO2 the relation

Jan 1, 1967

By J. A. Cahill, A. D. Kirshenbaum

Using an alumina or zirconia crucible with an alumina sinker or a molybdenum sinker coated with zirconium dioxide, the density of liquid iron was determined by the immersed-sinker method over the temperature range of 1800" to 2500°K. The density, with respect to temperature, is ex-Dressed by the equation Dg/cm = 8.523 - 8.358 X 10 T'K The molar Volumes and thermal coefficients of expansion were calculated. Iron, upon me1ting, was found to expand 3.5 pct. A basic knowledge of the physical properties of materials at high temperatures is becoming increasingly important. A check of the literature shows, that in spite of the importance of iron, very few measurements have been made of its physical properties in the liquid state. Density measurements have been made by Benedicks and his collaborators1g using the method of balanced columns, by Desch and smith4 using the immersed sinker method with an alumina sinker, by Lucas using the maximum bubble method5 and by Stott and endall' who used an alumina pyknometer. In the method of balanced columns, the difference in level of molten iron in two arms of a U-tube, together with the corresponding difference of pressure had to be measured. The formation of gas bubbles in one or both arms was a great source of error. These values are very erratic. They vary from 6.83 to 7.45 g per cm3 at the melting point (1805"~) and from 6.45 to 7.15 g per cm3 at 1890°K. Stott and Rendall determined the density at 1837"K, with a reproducibility of *0.2 pct. They used an alumina pyknometer fired to 1973°K. The vessel was filled in a vacuum furnace by immersion in the liquid metal. When thermal equilibrium was attained, the pyknometer was withdrawn, cooled, the ingot removed and then weighed. The chief disadvantage of the method was the difficulty of inserting the pyknometer without cracking it. The authors have been able to determine the density of liquid iron from its melting point up to 2500°K, by using the immersed-sinker method, with A1203 or ZrOz crucibles and A1203 or molybdenum sinkers coated with Zr02, Fig. 1. EXPERIMENTAL Apparatus. In these studies the source of heat was the carbon tube resistance furnace with an argon atmosphere described previously.7 Experimental runs were made using either Ala3 or ZrOz crucibles. The sinkers used were 1) pure A1a3 and 2) molybdenum coated with ZrOz. The crucible, 2 1/8 in. in diam and 3 in. high, was centered in the furnace on an Ala3 of Zr02 pedestal. The sinker, 1/2 in. in diam and 1 1/2 in. long, together with a counter weight, was suspended from an analytical balance into the melt by a molybdenum wire. Procedure. The procedure, as described previously,' consisted in measuring the weight loss of the sinker in the liquid iron while determining simultaneously the liquid iron temperature by means

Jan 1, 1962

NEW MEMBERS The following list comprises the names of those persons who became members during the month of December, 1913: Members ADAMS, CHARLES W., JR., Smelting, American Smelting & Refining Co., Murray, Utah. ARMSTRONG, FRANK H., Mechanical Engineer Vulcan, Mich. ARNOLD, JOHN B., Attorney-at-Law Room 840,200 5th Ave., New York, N. Y. BOYS, HARRY R., Mining Paso Robles, Cal. CAVANAGH, JOHN L., Min. Engr., Nova Scotia Steel & Coal Co.; Wabana, Newfoundland. CHOW, KAI CHI, Student 1120 Amsterdam Ave., New York, N. Y. CLARK, ARTHUR B., Mining Engineer 72 Harbour Bldg., Butte, Mont. CURLEY, JOHN R., State Mine Inspector P. 0. Box 633, Leadville, Colo. DAVIS, ANGUS W., Mining Engineer, Consolidated Mining & Smelting Company of Canada, Trail, B. C., Canada.

Jan 1, 1914

By F. Clerf

Blast-furnace practice in France is determined more or less by the character of the ores used. Some French ores are siliceous and others are calcareous, therefore by proper burdening a self-fluxing mix can be used. This is not always done, as, for instance, at the Caen furnaces of the Société Métallurgique de Normandie, where the Soumont ore of Normandy is used, which is a carbonate. This ore is crushed and calcined at the mines, yielding a product that is porous and well sized for blast-furnace consumption. The lines of the Caen furnaces are given in Fig. 1. Originally these furnaces had 16 tuyeres; six are plucked and these tuyeres are set in the lower part of the bosh. Operating data on these furnaces are given in Table 1. Table 1.—Operating Data, Caen Furnaces Kg. Lb. Blast-furnace burden per ton of iron: Soumont ore....................................... 200&2100 (44004650) Limestone...................................... 900-1000 (2000-2200) Basic Bessemer slag (bearing phosphorus).............. 100 (220) Scale.............................................. 35 (77) Manganese ores.................................... Coke.............................................. 1100-1200 (2420-2640) Coke analysis: Ash, per cent............. 9.5 H2O, per cent............. 4.0-10.0 Flue dust (approx.), kg. per metric ton.... 200 (440 lb.) Blast volume, cu. m. per hr.............. 83,000 (49,000 cu. ft. per min.) Preesure, lb............................ 12 Blast heat, deg. C....................... 650 (1200" F.) Top temperature, deg. C................ 250 (445O F.) Top-gas analysis, per cent............... CO2 9.3 CO 30.3 O2 0.3 H2 3.0 Production per 24 hr. about 510 tons. MINETTE ORES The most important ore deposits in France are in the west of Lorraine. They are called the "minette" ores and are of two classes-—siliceous and

Jan 1, 1937

By Rossiter W. Raymond

The manufacture of ferromanganese in the blast furnace having been the subject of considerable attention in the Institute, I beg to put on record a contribution to the discussion from a quarter hitherto not directly represented, namely, the St. Louis furnaces, near Marseilles in France, belonging to a company of which M. Jordan, a member of the Institute, is Managing Director. These furnaces commenced in 1862 to manufacture specular pig (fontes facettes) containing from three to six per cent. of manganese. In 1864 the regular production of spiegeleisen (fontes miroitantes), containing seven to ten per cent. of manganese, was inaugurated. At that time the Rhine was the only locality of this manufacture, and the Bessemer works of England and France obtained from Gernlany all their spiegel. From 1864 to the present time, the St. Louis furnaces have been advancing steadily the percentage of manganese in their product. From ferromanganese of thirty per cent. they had arrived, about two years ago, at a product containing seventy to seventy-five per cent., and for some time past they have been turning out what, as M. Jordan remarks, may fairly be Termed fonte de manganese, or manganese pig, instead of iron, since the percentage of iron it contains is not more than 8.5, while the percentage of manganese is 85, or ten times as great. This very high grade material has a peculiar appearance, entirely different from that of ordinary cast iron or spiegel. It is granular, and steely gray in color. The following analyses, communicated to the Sociètè des Ingenieurs Civils, by M. Jordan, show the composition of various products of the St. Louis furnaces:

Jan 1, 1879

By A. V. Deforest, A. R. Anderson, C. W. MacGregor

ONE of the important problems in the design of structures and machine parts subjected to rapidly applied loads is the determination of the strength and ductility of the material itself under such conditions. Realizing the need for such information, many investigations have been carried out in the past. Most of these experiments have been made using notched bars in bending either with the Charpy or Izod impact machine. While yielding valuable data on the effect of notches in the energy absorption of the material and on the condition of heat-treatment, this form of test does not lend itself readily to a determination of fundamental stress-strain relations. For this and other reasons, more attention has been paid recently to the tension impact test. An extensive literature already exists on the subject and only those investigations somewhat closely related to the present paper will be mentioned. For a more comprehensive list, the reader is referred to the Symposium on Impact Testing of the A.S.T.M., 1938. The work of Mann,1 Clark and Dätwyler,2 Nádai and Manjoine,3 Winlock and Leiter,4 Deutler,5 and Brinkmann,6 however, deserve especial mention. In most of the previous investigations on the subject, when stress-strain relations were obtained under high rates of loading, it was the common procedure to determine stresses based on the original area and strains based on the original length. Stress-strain curves were then constructed by plotting [So = ooT as a function of eo =o] where A o and Lo refer to the original area and gauge length, respectively. At present there exists a paucity of true stress-strain data in the impact problem. The advantages of constructing so-called true stress-strain curves in order to reveal the fundamental physical properties of the material for the tension test were discussed recently by one of the authors? It was shown that the true physical behavior of the material in the tension test could best be represented by plotting the average true stress, [S = P] as a function of [e = q' = log A-le = log Lo] where P, A, L, S, [e], and q' refer to the load, the cross-sectioned area while the load P is applied, the actual gauge length, the average true stress, the true strain and true reduction in area, respectively. Besides giving a better physical representation, the method has certain additional advantages in that the stress-strain curve so plotted becomes a straight line from the maximum load point to fracture. The construction of such curves, however, while comparatively simple for the slow rates of loading customarily used in the tension test, presents certain difficulties for tensile impact in that both loads and diameters are required throughout the test. The continuous measurement of test-piece

Jan 1, 1941

By O. W. Shimer, D. C. Helms, C. E. Brown

The early history and progress of anthracite stripping, from the first known operation at Summit Hill in 1821 through 1917, was covered in 1917 in a paper by J. B. Warriner,1 then chief engineer, now president of the Lehigh Navigation Coal Co., and stripping methods between 1917 and 1931 were the subject of a paper in 1931 by H. H. Otto,2 of the Hudson Coal Company. . The present paper is confined to methods used today on pitching beds in the western middle and southern anthracite fields. The anthracite industry, not unlike other large industries, had been affected for more than a decade by the adverse economic conditions of the country. High development and operating costs and the competition of other fuels caused some collieries to be closed temporarily, while others were permanently abandoned. In order to obtain a larger tonnage at a lower development cost, a larger stripping program was put into effect by many companies. In 1932, stripping operations accounted for 3½ million tons, or 7 per cent of the total anthracite production of the year, and in the next 10 years this increased until more than double that amount, or over 14 per cent of the total production, was from stripping operations. These figures represent the total production of the entire anthracite region; unfortunately, the figures have not been separated from the different fields. There are some operations in the southern and middle western fields where the tonnage obtained from stripping amounts to more than 30 per cent of the total colliery production. Stripping operations on pitching beds present difficult problems. Owing to the various geological formations, a different situation is encountered in nearly every stripping pit; and because of the proximity of an overlying bed, it is very often necessary to load the entire overburden into trucks and haul it out of the pit to the dump area, although back filling and casting is done whenever possible. Beds in the areas described in this paper pitch from 20" to 90 and some are on the invert in many sharp folds and faults. Planning The more successful strippings have had adequate engineering analysis. Some work is being done without much preliminary planning, but many strippings would have failed completely if close supervision by the engineering department had not been . maintained. Locations of stripping areas are determined as follows: I. By constructing cross sections over the areas and drilling sufficient diamond-drill or well drill holes to study the strata and to determine the location, thickness

Jan 1, 1944

CONTENTS PAGE ANDERSON, ROBERT J., and ENOS, GEORGE M.-Corrosion of Brass as Affected by Grain Size. Discussed by Henry S. Rawdon, Robert J. Anderson, Francis B. Coyle, William B. Price, and W. R. Webster 1 RAWDON, HENRYS., and MUTCHLER, WILLARD H.-Effect of Severe Cold Working on Scratch and Brinell Hardness. Discussed by W. H. Bassett, John Livermore Christie, John R. Freeman, Jr., W. R. Webster, William B. Price, Norman B. Pilling, D. J. McAdam, Jr., F. G. Smith, Zay Jeffries, F. E. Carter 3 WILLIAMS, ROBERT S., and HOMERBERG, VICTOR 0.-Relation of Heat Treatment to the Microstructure of 60-40 Brass. Discussed by 0. W. Ellis 14 Corrosion of Brass as Affected by Grain Size Discussion of the paper of ROBERT J. ANDERSON and GEORGE M. ENOS, presented at the New York Meeting, February, 1924, and issued as Paper No. 1282, with MINING AND METALLURGY, December, 1923. HENRY S. RAWDON,* Washington, D. C. (written discussion).-So numerous and so varied are the factors that affect the corrosion of metals that particular care is necessary in corrosion tests to eliminate so far as possible all extraneous factors. It appears to the writer that the question may well be asked as to whether all the necessary precautions have been observed in this investigation. It may be that the points to be mentioned were considered by the authors and found to be insignificant; however, there is nothing in the report to show this.

Jan 5, 1924

By Ralph Hultgren, Bernard York, David W. Mitchell

It is a well-known fact that magnesium-alloy castings are apt to be coarse grained if the melt is not superheated several hundred degrees above the melting point before casting. (The casting temperature varies according to the shape of the mold. A typical casting temperature is perhaps 1400°F.) British practice is to heat to 900°C. (1650°°F.) for 15 min., cool rapidly to casting temperature, and cast.1 In Germany superheating is carried out at 850° to 900°C. (1560° to 1650°F.) depending on the amount of scrap used. It is stated that further refinement will be obtained by prolonging the period of superheating or by increasing the superheat temperature to 950°C. (1740°F.).2 In the United States superheating is carried out at i600° to 1700°F. (871° to 927°C.), perhaps even higher in some places. It is stated that superheating effects are found as low as 1500°F. (816°C.), but several hours are required.3 These commercial treatments lead to grain sizes in sand castings that may vary from 4 to 8 grains per sq. mm.§ in heavy sections and from 60 to l00 in 3-in sections to perhaps 380 in thin sections. It is also generally known that the refining effect of superheating is lost if the melt is held for some time at lower temperatures before casting. Aside from these very qualitative statements, there is little to be found in the literature as to the effect of temperature and time of superheat on the final grain size. Because of the uncertainty of these factors, the Office of Production Research and Development of the War Production Board placed a research contract with the University of California, supervised by the War Metallurgy Committee. This research, which was done under the "Restricted" Project NRC-550, is the basis of this paper, which has been released for publication by the O.P.R.D. The material studied was an alloy prepared from carbothermic magnesium. The temperatures required for grain refinement proved to be widely different from those used in practice, as described in the statements in the first paragraph. This difference is attributed to the fact that the magnesium in the specimens was of carbothermic origin instead of the electrolytic magnesium in common use. MATERIALS AND METHODS The magnesium alloy studied was one of the most popular sand-casting alloys, with a nominal composition of 9 per cent aluminum, 2 per cent zinc, and 0.r per cent (minimum) manganese and the balance magnesium. This is designated

Jan 1, 1945

By E. H. Rennhack

Phase equilibria of the zinc-rich portion of the Zn-Fe-A1 system containing up to 20.0 wt pct Fe and Al have been investigated at 600°C (1112°F), 450°C (842°F), and room temperature by metallographic and X-ray diffraction techniques. The phase relationships were found to involve only those phases present in the three binary systems. THE presence of small quantities of aluminum (approx. 0.2 wt pct*) in zinc galvanizing baths is known to suppress the formation of Zn-Fe alloy layers within the coating.' As part of an extended investigation of this suppression effect and the alloy reactions involved, the zinc-rich corner of the Zn-Fe-A1 equilibrium system containing up to 20.0 pct Fe and Al was determined at 600°C (1112°F), 450° F (842° F), and room temperature. The present paper reports the findings of this study. The constitution of the Zn-Fe system has been reported by Raynor2 based mainly on the work of Schramm3-3 and Truesdale et a1.6 The solid solubility of iron in zinc is extremely small and lies between 0.0009 and 0.0028 pct in the range 150° to 400°C (302°to752°F). Within the temperature and composition range of interest, a eutectic reaction involving nearly pure zinc, liquid = Zn+FeZn13, is observed at about 419°C (786° F) and 0.018 pct Fe along with a peritectic reaction, FeZn7+ liquid e FeZn13, at 530°C (986° F) and 6.2 pct Fe. The latter reaction is sluggish due to the large proportipn of solid phase involved in the transformation. Halla et al.,7 identified the compound FeZn13 as monoclinic with a = 13.68, b = 7.63, c = 5.07, and B = 128°44'. The structure of FeZn7 was reported by Bablik, et al.,8 to be of hexagonal symmetry, belonging to either the C6v = C6/m mc or D46h = C6/mc space group. Divensions of the unit cell are a = 12.81A and c = 57.6a. The Zn-A1 diagram as composed by Raynor9 and later Gebhardt10 is characterized by a eutectic decomposition, liquid 382°C (720°F) and 95.0 pct Zn and a eutectoid decomposition, at 275° (527°F) and 78.0 pct Zn. The eutectoid reaction cannot be suppressed permanently by quenching. Above 275° (527° F), a and a' co-exist in a closed miscibility gap between 31.6 and 78.0 pct Zn. Both phases are fcc and have nearly the same lattice parameter. The maximum solubility of aluminum in zinc (B) is approximately 1.0 pct at the eutectic temperature. PROCEDURE Materials. The experimental alloys were prepared from both massive and powdered material. Cast alloys were composed from three zinc-base master alloys containing 8.0 pct Fe, 16.0 pct Fe, and 50.0 pct Al which were made from C.P. zinc, Armco iron, and

Jan 1, 1962

(Members are urged to send in for this column any notes of interest concerning, themselves or their fellow-members.) Members and visitors who registered at institute headquarters during October A. Adiassewich, St. Petersburg, Russia. Charles W. Merrill, San Francisco, Cal. A. F. Lucas, Washington, D. C. Carl J. Trauerman, Butte, Mont. Allan J. Clark, Lead, S. D. Herbert B. Cox, Boston, Mass. Prof. Loewinson-Lessing, St. Peters- James W. Malcolmson, Kansas City, Mo. burg, Russia. A. E. Sunderhauf, Paramaribo, Dutch F. Maury Gillespie, Abangarez, Costa Rica. Guiana, S. A. M. Gardner Talcott, Irvington-on-Hudson, N. Y. D. W. Brunton, Denver, Colo. A. P. Watt, Newark, N. J. Dwight E. Woodbridge, Duluth, Minn. S. A. Taylor, Pittsburg, Pa. Alexander Fyfe, Boston, Mass. Ralph Wilcox, Miami, Ariz. Robert A. Seip, Wilkes-Barre, Pa. William J. Cox, Denver, Colo. A. J. Eveland, Boston, Mass. E. P. Ross, Duquesne, Pa. M. F. Sayre, Brewster, N. 1. H. Mortimer-Lamb, Montreal, Canada. Albert Sauveur, Cambridge, Mass. F. L. Grammer, Leesburg, Va. Robert H. Leach, Brockton, Mass. R. R. Moore, Mexico City, Mex. Steinar Foslie, Kristiania, Norway. Charles E. van Barneveld, San William A. Wong, Honolulu, Hawaii. Fran¬cisco, Cal.

Jan 11, 1913

By G. R. Speich

A cellular precipitation reaction in which cells consisting of an Ni3Ti (DO24) phase and austenite are formed has been studied in an austenitic Fe-30 Ni-6 Ti alloy. The variation of the growth rate and interlamellar spacing of the Ni3Ti cells with temperature has been determined m the range 400" to 975°C; the interlamellar spacing is proportional to the degree of undercooling; the growth rate can be expressed by an equation of the form G = K?T)2 exp(-Q/RT). The habit of the Ni3Ti lamellae is (001)Ni3Ti (111)y;[010]Ni3T2 [010]y. An almost perfectly coherent interface is formed between Ni3Ti lamellae with this orientation rela -tionship and the intervening austenite. This first Ni3Ti cellular product is subsequently consumed by a second cellular reaction of much coarser spacing. CELLULAR precipitation reactions have been studied in copper-base,1,2 Au-Ni,3 pb-sn,4 and iron-base ferritic5,6 solid solutions, and this mode of precipitation has been treated theoretically by smith," Turnbull,8,9 cahn,10 and more recently by bohm.11 In the case of substitutional austenitic iron-base alloys little or no data are available, Cellular precipitation reactions are well known in austenitic nickel-base alloys12,13 but usually these reactions do not proceed to completion because of general precipitation occurring in the matrix, and they have not been studied in detail. Precipitation from an austenitic Fe-30 Ni-6 Ti alloy was studied as part of a larger investigation of the mechanisms of precipitation from substitutional iron-base alloys. This alloy, austenitic at high temperatures, decomposes at lower temperatures by a double cellular precipitation reaction. The first decomposition product consists of alternate lamellae of an Ni3Ti(DO24) phase and austenite. The reaction proceeds to completion, consuming all of the original austenite. This first cellular product is subsequently consumed by a second cellular reaction of much coarser spacing. The first cellular reaction was studied in detail by light and electron microscopy, hardness measurements, and by X-ray and electron diffraction. Interlamellar spacings and growth rates were measured during isothermal aging in the range 400" to 975°C. The orientation relationship between the Ni3Ti and austenite lamellae was determined and indicates that an almost perfectly coherent interface exists between the two phases. This first Ni3Ti cellular reaction is of particular interest because it occurs over such a wide temperature interval. This allows cellular growth rates and interlamellar spacing data to be obtained for much larger degrees of undercooling than reported hitherto. MATERIALS AND EXPERIMENTAL PROCEDURE The Fe-30 Ni-6 Ti alloy was prepared from electrolytic iron, Mond nickel shot, and sponge-purity titanium* by vacuum melting in a zirconia crucible

Jan 1, 1963

By S. Stutz

Coal, like most other minerals, only exceptionally occurs in a sufficiently pare state to he directly available for general manufacturing purposes. And even where this is the case, the small coal or slack is usually more impure than the lump coal, as the slate, clay, etc., from the roof and bottom of the vein become mixed with it in the handling it undergoes. These impurities often exceed ten or more per cent. in addition to the impurities of the coal itself. The most common impurities of the coal are slate, or shale, clay, and sulphur. The latter occurs in different forms, but moat frequently as bisulphide of iron, or iron pyrites, and as sulphate of lime, or gypum. In both cases the impnrities add greatly to the amount of ash, and where they are present in considerable quantities the raw coal, and still more the coke made from it, is unfit for the manufacture of iron. Coke will coutain on an average at least fifty per cent. more ash and sulphur than the ram coal from which it is made. To the manufacturer of iron every additional per cent. of ash which his coal or coke contains is a source of additional expense, seemingly small, and yet very important in the aggregate. In the blast-furnace, for instance, the ash must be heated up to the melting-point, and, since it is composed largely of refractory substances, the consumption of carbon in melting it will be equal to at least one-half of its weight; that is, a certain part of tile coke is consumed for the melting and fluxing of the ash and is lost. Besides this, it is well enough known to the iron-master that coke containing lees ash makes the &lag or cinder more liquid and less incliner1 to stick to the walls of the furnace. Fuel containing much sulphur produces generally a white iron, poor in carbon, while from the same ore arrd flux, with a pure fuel, a good foundry iron might be obtained. The work of separating slate, sulphur, etd, from the coal has as yet only been successfully accomplished by the washing process. This process depends for its success on the differences in the specific

Jan 1, 1881

By A. J. Hatch

Recent disclosures concerning strengthening of anisotropic sheet materials under biaxial stresses are reviewed. This biaxial strengthening has been termed "texture hardening" by Backofen and is related to the normal anisotropy parameter, R. Measurements of R made on three annealed titanium alloys indicate a Ti-4Al alloy will have the greatest potential for texture hardening, followed in order by Ti-5Al-2.5Sn and Ti-6Al-4V. Relative to sheet texture, a review of the deformation mechanisms in titanium alloys would indicate that a preferred orientation for "texture hardening" is where the (0001) pole is normal to the sheet plane. This was confirmed by determination oj (0001) pole figures for the above three alloys. High R values are related to pole figures with (0001) normal to the sheet plane, whereas low R values are related to pole figures with (0001) split in the transverse direction from the sheet normal. PUBLISHED work by Backofen et al. 1 and Hosford and Backofen2 based on hill's' mathematical theory of yielding in anisotropic metals has indicated that significant strength advantages under biaxial stresses are possible in hcp alloys, provided an ideal (0001) [1010] sheet texture exists. This tendency to strengthen under biaxial stresses has been termed "texture hardening".1 It can be quantita- tively characterized by a strain-ratio parameter, R, where R may be determined from the ratio of natural width strain to natural thickness strain as measured on a uniaxial test specimen cut parallel to the rolling direction. If R is greater than 1.0, then strengthening under biaxial tension would be predicted. Considering the a titanium alloys which have an hcp crystal structure, Williams and Eppelsheimer4 have reported that commercial-purity grades deviate from the ideal (0001) sheet texture mainly in an approximate 30-deg rotation of the basal plane, toward the transverse sheet direction. However, McHargue et a1.5 have shown that the angle of rotation of the basal plane is sensitive to alloy content. In particular, a titanium alloy with 3.8 pct Al was reported to have the ideal (0001) [1010] texture after cold rolling. Additionally, Backofen et a1.1 using plane-strain compression tests have reported R values greater than 5.0 for the commercial 0 alloy Ti-5A1-2.Sn (110-AT). In view of these findings, a program was initiated to further determine the potential of commercial Ti-5A1-2.5Sn and an experimental Ti-4A1 alloy with respect to "texture hardening". Also, because of its wide commercial use, Ti-6A1-4V was included in the investigation. BIAXIAL-STRESS THEORY FOR ANISOTROPIC MATERIALS Backofen ef al.,1 based on the mathematical theory of Hi11,3 has introduced the concept of "texture hardening". In this work, it was shown that possi-

Jan 1, 1965

By R. J. Reynik

A semiempirial small flunctation theory of diff- sion in liquids is presented, which employs a fluctuation energy assumed quadratic for a small atomic or molecular displacement and Einstein's random-iralh model. The resulting diffusion equation is given by In these equations. D is the diffusivity, is the average liquid shite coordination number (at interatomic distance d. cm. T is the absolute temperature, xu. em, is (the diffusive displacement. K, is the quadratic fluctuation energy force constant, and rg, cm, are the radii oj diffusing atoms A and B, respectively. The quantities Xn and K are calculated from the computer-filled values of the slope and intercept. respectively. The radius of self-diffusing atom or radii and of diffusing atoms A and B are eta United and compared with values reported in the literature.. The predicted linear variation of diffusivity with. It tempera lure htm been observed in approximately thirty-iire metallic liquid systems, and in over seventy-fiee other liquid systems, including the organic .alcohols, liquified inert gases, and the molten salts, ALTHOUGH the average density within a macroscopic volume element of liquid is constant for fixed total number of atoms. pressure. and temperature, there exist microscopic: density fluctuations within the respective volume element. As such the microscopic volume available to an atom and its Z first nearest neighbors at any instant of time fluctuates above and below the average volume available to these atoms. If one assumes that liquid state atoms vibrate as in a solid. and further postulates that the mean position of any atom in the liquid state is not stationary. but shifts during every .vibration a distance 0 5 j 5 xo. then every atom in the liquid state continuously undergoes diffusive displacements which vary in the range 0 5 j 5 ro. Mathematically. for a binary liquid system consisting of atcrms A and B. the maximum diffusive displacement. .YO, is defined by the equation: where d is the average liquid state interatomic distance at specified liquid state coordination number Z. and v~ \ and vg are the effective radii of diffusing atoms A and B: respectively. For self-diffusion. r^ equals rg , and Eq. [I.] reduces to: It is interesting to note that Eq. [l] or [2] can be used to compute the radii of the diffusing atoms, provided one had an experimental evaluation of xo. As such. the computed radii could be compared with metallic or crystallographic ionic radii to ascerlain the electronic character of the diffusing atoms. Thus it is proposed that in the liquid state the n~otion of an atom relative to its original equilibrium position of oscillation represents the thermal vibration of any atom and its Z first nearest neighbors. while the small and variable displacements. 0 5 1 5 xc,. of the centers of oscillation represent the complex diffusive motions of the atoms at constant temperature and pressure. This is consistent with data obtained from slow neutron scattering by liquids1 ' and resembles an itinerant oscillator model of the liquid state.'" It is further postulated that the atomic displacements characterizing the liquid state diffusion process are essentially a random-walk process. As such. it nlay be described by Einstein's equation:' where D is the diffusivity. sq cm sec-'. j2 is the mean square value of the diffusive displacement. and i> is the frequency of density fluctuations giving rise to diffusion. FORMULATION OF DIFFUSION EQUATION The effective spherical volume occupied by an atom, as a consequence of a microscopic density fluctuation which enlarges the volume available to any atom, exceeds its average liquid state atomic volume by an amount: where AV is the enlarged spherical volume, v is the radius of the diffusing atom. and j is the elementary displacement distance from the original center of oscillation of the vibrating atom to a new center of oscillation position. For small atomic displacements. where c is a constant whose value depends upon the assumed geometry of the enlarged volume. For a spherical increase in volume, c equals 4nr2. Following the treatment of Furthl' and ~walin." assuming the enlarged volu~nes AL7 for the diffusing atoms are distributed in a continuunl. the probability of finding a fluctuation in the size range 0 5 j 5 xo defined by Where c includes the geometric constant cl and Eij) is the fluctuation energy causing the volume change. But the proposed model assumes all the Z first nearest-neighbor atoms are centers of oscillation. and hence the probability that any of these atoms is adjacent to a fluctuation of magnitude 05j5xo is unity. Thus:

Jan 1, 1970

Abbey, Robert Graham, District Mgr.. The W. W. Sly Mfg. Co., 50 Church St.. New York, N. Y. '21 Abbott, A. N., Mines Supt., Mazapil Copper Co., LtdConcepcion del Oro, Zac., Mexico. '28 *Abbott, Argyle Campbell, Dev. Dept., E. I. du Pont de Nemours & Co., Wilmington, Del. '29 Abbott, Clarence E., V.P., Charge of Raw Materials, Tenn. Coal, Iron & R. R. Co., 1242 Brown-Marx Bldg.. Birmingham, Ala. '04 Abbott, Louis Benjamin, Chief Engr., Elkhorn Div., Consolidation Coal Co., Jenkins, Ky. '16 Abeel, George H., Jr., Cons. Min. Engr Box 427, Santa Monica, Cal. '18 Abel, Albert E., Asst. to Pres., Valley Mould & Iron Corp Hubbard, Ohio. '19 Abel, Raymond L., Asst. Prof., Dept. of Pet. Refin., Univ. of Pittsburgh Pittsburgh. Pa. '28 Abeel, Leo M., Research Engr., Sullivan Concentrator Chapman Camp, B. C., Canada. '31

Jan 1, 1929

Jan 1, 1903

By R. A., Pallanch

SO many variations of lead-zinc ores occur in nature that it is impossible to state any rules that will apply to the concentration of ores of this type. Some have lead and zinc in approximately equal amounts; others may have pre- dominant amounts of one or the other metal. There are gradations from all sulfide to completely oxidized minerals. Some such ores carry little pyrite, others contain much more pyrite than they do lead and zinc combined. The behavior of ores in flotation is largely a function of their lead-zinc ratios. their content of pyrite or pyrhotite, the nature of existing soluble salt conditions, the character of the gangue constituents: and the speed with which the minerals float. For the purposes of this paper only those lead-zinc ores handled commonly in present-day flotation practice will be considered. These are practically all-sulfide ores with relatively minor degrees of sulphatization or oxidation.

Jan 1, 1936

By Harry M. Mikami, Harold A. Heiligman

The term chromite is often used to cover all chrome ores and concentrates which are the designations actually employed by most industrial users and producers. Chromite is, of course, the predominant mineral in chrome ores which are aggregates of chromite and gangue minerals, most commonly magnesian silicates. Most chrome ores now used are petrographically chromitites which is a rock, rather than an individual mineral term. The title of this chapter, following past usage, is meant in the broad sense. Chromite is the only primary commercial source of chromium. This book is intended to deal only with nonmetallic minerals and rocks. Chromite uses are both metallic (ferroalloys) and nonmetallic (refractories and chemicals), but any discussion of mineralogy, geology, and mining is common for all types. A number of the major commercial ores are interchangeable, and their uses are determined by economic considerations. Mineralogy COMPOSITION [Chromite is a term embracing a wide range of chromium-bearing spinel*-group minerals the compositions of which can be expressed as (Mg,Fe2+)0.(Cr,AI,Fe3+ )203.t This can be further generalized to R2+O.R23+03 and the molecular RO: R,03 ratio is generally close to one. The exact composition may be arbitrarily expressed as a solid solution of six end-members, MgAI2O4, MgCr2O4, MgFe2O4 FeCr2O4, FeA12O4, and Fe2+.Fe23+04 with the proportions of each stated or plotted in the six-cornered prism of Johnston and Stevens61 or this scheme may be simplified to comprise only three endmembers making up a composition triangle, Fig 1. [ ] FIG 1-Triaxial composition diagram showing molecular compositions of chromites listed in Table 1. The RO.Fe2O3 corner includes Ti02 norms listed in the table. Note that the high-alumina chromites (1, 2, 3, 9), form a cluster well apart from the high-Cr2O3 chromites. There is a tendency for high-iron chromites to be higher in Fe2O3 + TiO2 but it is not a consistent or systematic relationship. The MgO/RO ratio must also be known to characterize the chromite chemically. Simplest and most convenient method is Thayer's' in which a chromite such as (Mg.65Fe.352+)O.(Cr.40Al.50Fe.103+)203 would be written as (Mge,) Cr eAlo. The molecular pro- portions of ferrous and ferric oxides can be seen at a glance as the divalent and trivalent oxides]

Jan 1, 1960