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By W. S. Holt, K. A. Grange, E. T. Tkac

Quantitative knowledge of the time clement involved in austenite transformation in a particular steel provides a sound basis for understanding and planning heat-treatment. Such knowledge is conveniently obtained by measurement of austenite transformation as it occurs at each of a series of temperature levels. The results of these measurements usually are summarized in the form of the now familiar isothermal transformation diagram (I-T diagram, TTT diagram, or S-curve). Although a considerable number of such diagrams already have appeared in the literature, there remain many compositions of commercial importance for which no I-T diagram is available. The diagram for many such steels may be predicted from published data with sufficient accuracy for most practical purposes, but for others no satisfactory prediction can be made because the effect on austenite transformation of one or more of the important alloying elements present is not well enough known. Such a steel is Nitralloy, Type 13s-Modified, which, containing about 1.25 per cent aluminum, differs from any whose I-T diagram has been published. This paper presents results of a study of the isothermal transformation behavior of a sample from a commercial heat of this aluminum-chromium-molybdenum steel, together with pertinent supplementary data including the equilibrium transformation temperatures (Aeaand Ae,), the temperature range of martensite formation, and the end-quench harden-ability. These data are directly applicable to the hcat-treatment of this type of steel and are of interest in revealing some of the fundamental effects of aluminum as an alloying element in steel. Material All specimens were prepared from a 1 1/4 i-in. diam bar forged from a 5 by 5-in. billet from a commercial heat made in an electric arc furnace. The composition of the bar was; C, 0.41 per cent: AIn, 0.57: P, 0.016: S, 0.005: Si, 0.24: Ni, 0.17: Cr, I.j7: Mo, 0.36: All 1.26. The forged bar was normalized from r750°F (95s°C) and then tempered for one hour at rzoo°F (650°C), this tempering treatment having been given to facilitate the machining of specimens. Equilibrium Transformation Temperatures In hypoeutectoid steel the minimum temperature at which austenite is completely stable, Aep, and the maximum temperature at which austenite is completely unstable, Ael, are of great significance in heat-treatment. Since these temperatures are dependent upon com-

Jan 1, 1948

THE following statement is contained in an article entitled "Mortgaging the Future." by Walter C. Teagle, president of the Standard Oil Co. of New Jer-sey, appearing in the current issue of the Lamp, the official organ of the Standard Oil Co.: "During the last eight months the domestic daily production. of crude oil has risen 300,000 bbl.. which means that no less a volume than 2,500,000 bbl. now are coming to market each day. . . . Every twenty-four hours 250,000 bbl. more than the consumer required are being added to our surplus oil storage. The temporary advantage of cheap petroleum products and the availability of fuel .oil, for a widespread use as a substitute for coal are not being weighed against the time when scarcity may follow on the heels of plenty and the public of tomor-row may have to pay for today's excesses. The over-production of crude and its consequences constitute a problem of national import which far outweighs the temporary advantages either to a part of the industry or to sections of the public.

Jan 8, 1927

The following delegates were appointed to the National Conservation Congress on May 2, 3, and 4, 1916, in Washington, D. C. HENRY S.. DRINKER, a GEORGE OTIS SMITH, A. F. Lucas, - W. L. SAUNDERS, VAN H. MANNING. President Ricketts was appointed delegate to the dedication ceremonies of the new buildings of the Massachusetts Institute of Technology in June. W. L. Saunders was appointed delegate to the ceremonies in celebration of the 150th Anniversary of the founding of Rutgers College to be held in October. George C. Stone was appointed delegate to the meeting on Standard Screen Scale of the U. S. Bureau of Standards. George D. Barron and Thomas T. Read were appointed delegates to the Second National Exposition of Chemical Industries to be held in New York in September. It was resolved, that the Institute shall pay the transportation of the Secretaries of the Local Sections to and from the Arizona Meeting. It was resolved that certain general topics' should be selected for discussion at the next meeting of the Institute and a session devoted to each.

Jan 6, 1916

By Robert W. Bergmann

Twenty years ago, the standard voltage for stripping machines was 4160 v and few people even thought of using a higher voltage. It was adequate for the machines of the day, which seldom exceeded 2500 hp, and higher voltages were considered to be too expensive and even dangerous. Then, in 1956, a 4500-hp machine was placed in operation and it was determined, with some reluctance, that it should operate on 7200 v. The next step, to 14,400 v, was taken in 1964 and the latest, but perhaps not final, step was made in 1967, when voltage was increased to 25,000 v. Today, 4160 v is considered almost obsolete and 7200 v is generally considered standard. However, a few mines are using 14,400 v and some eight machines soon will be operating on 25 KV, indicating that the technical and safety problems have been solved and that there must be some merit to the higher voltages. Thus, it is logical to question, "How do I determine the best voltage for my operation?"

Jan 12, 1972

By W. H. Tuttle, H. R. Ahlquist, A. J. Carlson

Variations of the EVOP technique are accepted as the foun- dation in the development of Erie Mining Company's mining, concentrating and pelletizing complex at Hoyt Lakes, Minnesota. The basic one-variable- at-a-time technique served its purpose through the laboratory pilot plant as well as the full-scale production sized pilot plant. However, recognition by Erie Mining Company management of the potential of computer application and statistical experimentation in plant operation and testing led to acquisition of an IBM 1620 computer in 1961. Adaptation of established techniques in statistically designed experimentation and analysis of results is presented in actual case form including the following: 1. Determination and use of variance, standard deviation, standard errors; application of t-test in determining true differences between daily aver ages of product assays; formulation of quality control limits; determining sample size; and application of normality tests will be discussed. 2. Use of mathematical modeling and regression analysis for establishing mill storage conditions based on bin level indicator lights. 3. Polyvariable random balance design of a balling circuit test and resultant identification of primary control variables.

Jan 1, 1969

Mr. Brown : .That part of the Standard Company's plant which has been added since the publication of Mr. Leggett's paper, and is described in mine, renders the single-phase, alternating system, which Mr. Hale has called " unelastic," much more elastic than it had been. The original plant at Bodie was substantially the same as the Telluride plant mentioned in his paper. The machines came from the same shops, and were practically the same; but while the Telluride Company has changed completely to a polyphase system, the Standard Company has retained its original plant, but has belted on a directcurrent generator at the receiving end, thereby converting the water-power into electricity, electricity into power, the power into electricity, and finally again electricity into power for use in the mines. This is a roundabout course, to be sure, but it shows that there are possibilities even in the out-of-date single-phase system. The only point perhaps, that deserves particular notice with respect to the hoist is the fact that the rheostat, or starting-resistance, was not built originally

Jan 1, 1897

By C. W. Hill

IN a previous article preliminary experiments were described, indicating the possibilities of a quantitative spectroscopic method for the determination of small amounts of lead in copper, which would be accurate and rapid, and could be carried out in the refining plant by one not skilled in chemical analysis. The present paper deals with the development of the method in the factory, giving the details of apparatus and its standardization, and presenting a comparison of the accuracy of the method with that of the standard electrolytic determination. (For variations and other applications of the method, the reader is referred to the first article.) FIG. 1.-STEPS IN THE ELIMINATION OF LEAD. (The lead line, at point 105.8 in the violet portion of the spectrum, is seen between the two copper Lines,-102.29 and -106.29, lying close to the latter. The crowded faint lines are due to the carbon are.) 1. OUTLINE OF METHOD A carefully weighed sample (0.4 gm.) of the copper to be tested is placed in a cavity in a graphite positive electrode. An arc capable of

Jan 10, 1918

By J. W. Leonard, B. A. Donahue

A method is described for incorporating coal petrography into mining and preparation plant quality control based on conventional analyses. Complete analyses are made of each of the uniform and relatively distinct petrographic bands in a coal face. With this information it is possible to develop petrographic standardization curves. These curves permit diverse coal characteristics to be rapidly monitored by application of a few standard coal tests. Single seam quality control is discussed in this paper. Inquiries continue to be made about coal petrography, and specifically, about whether coal petrography should be applied more extensively in the coal industry. Coal petrography is the study of the distinct physical, optical, and chemical increments which make up the organic rock mixture which we know as coal. Petrography can be applied by any coal company or at any coal mine where conventional coal analytical facilities are available and where additional resources can be allocated for an increased number of determinations. This first paper of a two part series includes (1) a proposed conventional approach to single seam petrography based on the development of petrographic standardization graphs and (2) some informative and supplemental interrelationships involving coal characteristics developed as a result of this research. In the second part of this series, to be published at a later date, those petrographic characteristics of bands taken from many different coal seams located over wide geographic areas which can be closely related to each other will be considered. These findings will be examined looking toward the development of a comprehensive, conventional approach to coal petrography which can be used as a common basis for multi-rank petrographic standardization graphs. Implicit to the understanding of coal petrography is the well established fact1,2 that the individual analyses of distinct petrographic bands often differ widely from the average analysis which is used to characterize a whole coal seam. In fact, a distinct and minor banded increment of coal in a high volatile seam may actually be a medium or low volatile coal with an analysis similar to the average analyses of seams located in distant coal fields. During the mining of coal, much degradation is caused which tends to randomly scatter coal bands. The degraded, scattered, and physically separated constituents of distinct petrographic bands are processed side by side in the coal preparation plant as distinct petrographic fractions with particles grouped according to a narrow size range (which derives in part from common hardness), specific gravity, and-or surface chemistry. Tile data obtained from numerous analyses made on each of the bands of any given coal seam, although diverse, can be readily interrelated. Indeed, these interrelationships can be developed into a series of nomographs or petrographic standardization graphs to serve as a basis for developing a conventional petrographic* program. Thus, by analyzing one property (for example, ash) of a selected petrographic fraction collected or separated from the flow of coal in a preparation plant, it should be possible to estimate the other physical, chemical, and thermal properties of this fraction by referring to the petrographic standardization graphs. It follows that any or all petrographic fractions in the total coal flow originating from a single coal seam can be rapidly monitored for many properties on the basis of a single analysis run on each fraction. In recent years coal petrographic research has concentrated heavily on that phase of this work which involves microscopic reflectance measurements made at many minute and selected points on a coal briquette surface.3,4 Thus, the percentage of the total number of reflectance measurements that fall into each of a consecutive series of arbitrarily chosen reflectance classes are used to characterize coal. This procedure is analagous to using the face of a coal briquette to represent the reflectance characteristics present at the face of a coal seam. Moreover, by analyzing petrographic fractions of known and uniform optical properties it is possible to closely relate reflectance to other coal characteristics. For example, reflectance has long been known to be related to such

Jan 1, 1968

My question relates to tundish nozzle plugging on aluminum-killed heats. North Star has avoided this problem by silicon deoxidation. What has been Inland's experience with this problem on open-pour and submerged nozzle pouring?

Jan 1, 1972

By Tong Guangxu

INTRODUCTION Throughout the world, the caving mining methods of ore-draw under the overlying waste rock are sublevel caving in Sweden, block caving in U.S.A. and forced block caving and sublevel caving with sill-pillar in U.S.S.R. These caving methods are of high efficiency, low cost and large production (especially the block caving method) when compared to opencast mining. From the ore production of all under- ground mines, the largest annual production of underground metalliferous mines in the world is caving methods. The sublevel caving in Kiruna Iron Mine of Sweden has reached annual ore production over 20 million tons in 1974. The block caving in Climax Molybdenum Mine and San Manuel Copper Mine of U.S.A. both have produced about 40 thou- sand tons of ore per day in 1971. At the same time, the productivity of Kiruna was 12 thousand tons of ore per man-year, Climax 42.8 tons (48.3 short tons) per man-shift and San Manuel 29.01 tons (32.1 short tons) per man-shift. The main feature of this group of mining methods is the underground extraction of ore from beneath overlying caveable waste rock. Since the loss and dilution of ore are inherent (sometimes to a great extent), the control of ore-draw in these methods as com- pared with other methods is very important. Consequently, concerned Universities and Research Institutes have devoted great amounts of research on ore-draw theory and control management which has provided positive results to mine production, and has apparently promoted the development of the caving methods. During 1979 in China, metalliferous underground mines accounted for 15.22% of the total iron ore produced, while also accounting for 56% of total non-ferrous production. According to the mining methods, sub level caving in the principal underground iron mines counted for about 56.74% of total principal underground iron mine production, but only about 1% of total non-ferrous underground mine production. Relative to forced block caving and sublevel caving with sill pillar, the Chinese non-ferrous under- ground mines estimated about 35% of total non-ferrous underground mine production from these two methods, mainly from the latter. From the trend of development of underground metalliferous mines in China, the percentage of production in caving will be increased in the future, especially in block caving and forced block caving which have already been given great attention in the mining circle. In these types of mining methods the ore is drawn from the stope under a large area of overlying waste rock, which complicates the basic regulation and control of ore-draw, but provides lower loss and dilution than sublevel caving. Because of these reasons, the Kiruna Iron Mine in Sweden is intending to change its sublevel caving by testing a sublevel shrinkage caving method and considering a large area of ore-draw beneath the stope as an advantage. Therefore, the basic regulation and control management of ore-draw under a large area, as practiced in China, will be discussed in this paper. BASIC REGULATION OF ORE- DRAW FROM CAVING STOPE The aim of studying ore-draw under a large area of overlying waste rock is to se- cure a planned draw schedule that guarantees a certain plane of interface between ore and waste rock, and controls the change of its shape in spatial position for reducing ore loss and dilution during the draw process. Presently, the ellipsoid theory is comparatively near the actual attitude of ore-draw from the cave. 1. Ore Drawn Out from Single Drawpoint Laboratory testing and practical experience all show that after a certain amount of ore has been drawn out from a drawpoint, its original shape in the stope before drawing is more or less similar to an ellipsoid, hence the name "draw ellipsoid." This draw ellipsoid is cut at the bottom by a horizontal plane corresponding to the raise of the drawpoint, and its volume can be calculated by the following formula:

Jan 1, 1981

By B. Egeberg

BRITANNIA metal is a white alloy consisting primarily of tin and antimony, the tin greatly predominating. The alloy usually contains a small amount of copper and occasionally very small amounts of one or two, other metals, such as bismuth, zinc, and lead. It is capable of being cold-rolled, it takes a high polish, and it is fairly noncorrosive; properties which make it a popular metal for many household and traveling utensils. Britannia metal is similar in many respects to pewter and has largely replaced pewter in the arts, but it should not be confused with that alloy, because pewter is essentially a tin-lead alloy, while Britannia is a tin-antimony alloy. In view of the fact that so little has been published concerning Britannia metal, the authors feel justified in presenting the results of their investigation, particularly since the behavior of this alloy under cold rolling and heat treatment differs so greatly from that of other metals and alloys. The old craftsman, engaged in the making of ornaments or tableware, heated the cold-rolled sheet metal or his finished product to a straw color corresponding to about 375° F., claiming to produce thereby a harder and more rigid article. The fact that possibly led him to this heating was that a reheated article or sheet made from Britannia metal has a distinct metallic ring when struck a sharp blow, whereas an unheated article or sheet has a leady, dead note. No doubt he has associated the metallic ring with a greater rigidity and strength, and justly so, as will be seen later.

Jan 1, 1928

By F. Peter

Technical progress takes place in two directions: the improvement of methods, affecting the quality of the product; and increase in the economy of operations, affecting its cost. In the iron-industry, practice is pretty well settled, and revolutionary changes of method are, for the present, not to be expected. Hence, in this industry, the principal endeavor is to reduce costs by the use of labor-saving inventions, such as the machines brought into use during the last decade. But it is not alone necessary to reduce the labor-cost; complete economy requires also a saving in raw material. Under this head we may rank the coal employed as metallurgical fuel; and it follows that progress includes the economic use of fuel, so managed as not to injure quality of product. In the present paper it will be shown how, by suitable utilization of the heat from the furnace, a large portion of it may be made available for other purposes. Such utilization of waste-gases is important in all industries which employ furnaces (especially heating-and smelting-furnaces); and in the first rank of these stand the iron-, glass-, and porcelain-manufactures. The following pages are devoted chiefly to the waste-gases of smelting-works, and especially to those reverberatory-furnace gases which are not combustible.' The object of metallurgical furnaces is either to fuse the material charged or to bring it to a high temperature required for further mechanical manipulation. Leaving out of consideration for the present the reverberatory fusion-furnaces, we have to do with the heating-furnaces employed in connection with rolls, hammers, or hydraulic presses. The temperature to which the material must be

Jan 1, 1914

By J. D. Exner

With the introduction of rotary drilling in the Gulf Coast area, some thirty-two years ago, and its subsequent spread to other producing localities in the United States, there has been a constant change in the design of equipment. Only the general features remain, namely the rotating drill stem and the circulating mud. Only recently have the properties of mud and their behavior received attention from petroleum engineers, but circulating problems in present deep drilling demand further study and understanding. It is the purpose of this investigation to determine the relative changes in the apparent viscosity of muds with changes in temperature and to discover other physical effects due to heat. Very little information has been published regarding the effects of temperature on the viscosity of drilling muds. Maustl states: "The viscosity of most muds is decreased on heating, but the interesting thing is that the degree of flocculation is also increased on heating. There will be a greater tendency to seal off formations at high temperatures than at low temperatures." With regard to the effect of temperature on viscosity and yield point, Herrick2 states: "The variation of yield point and viscosity of mud with temperature.....is not very clearly brought out by the data available. Both appear to decrease slightly with increasing temperature up to 200' F." The experimental results presented in this paper further emphasize this point. Two types of viscosimeters are available for measuring the apparent viscosities of drilling muds: the efflux tube type as used by Herrick3 and Marsh, and the torsional type such as the McMichael or the Stormer viscosimeters. Because of its extensive use in measuring the apparent

Jan 1, 1933

By D. S. Cahn, D. W. Fuerstenau

Specimens of glass, plexiglass, and naturally occurring minerals were irradiated by a 15-joule ruby laser pulse to determine criteria for the fracture of nonmetallic solids by internal thermal stresses. Fracture did not occur in those specimens with either a very high or very low internal absorptance or with a high spectral reflectance. If significant amounts of melting and vaporization do not occur at the surface of irradiation, the specimen will fracture if a derived 11fracture stress" exceeds the ultimate tensile strength of the specimen. The purpose of this investigation was to determine criteria for the fracture of nonmetallic solids by internal thermal stresses which are caused by absorption of laser irradiation. A laser produces a very short pulse of light which has a high energy density distributed over a very narrow part of the visible spectrum. The laser system used in this investigation had an energy output of 15 0 joules at a wavelength of 6940 A. Fracture in a non-metallic solid, then, would be caused by the absorption of light energy by that solid, and subsequent conversion of this energy to heat or mechanical energy. Fracture is caused by internal stresses that result from rapidly imposed nonequilibrium thermal gradients. ANALYSIS OF CONDITIONS FOR FRACTURE BY LASER IRRADIATION For this analysis, the laser beam is assumed to be circular and centered on the junction of the major and minor axes of a rectangular specimen. The laser beam forms a cylinder of radius rb extending through the specimen width. The beam cylinder may be then thought of as a heated mass constrained by a surrounding unheated mass. The instantaneously heated cylinder will at-

Jan 1, 1968

By J. V. Emmons

THE processes of hardening and tempering steel tools within the past 15 or 20 years have been so developed that the forward strides of the industry can scarcely be followed by the average observer. No small part of the credit for this phenomenal advancement is due to the improved methods of measuring the high temperatures necessary. Pyrometry has made possible the discovery and use of the many special alloy steels the wonderful properties of which are revolutionizing the industrial world. So sensitive are these steels to changes of temperature that often a variation of only 10° F. at a critical point of the heat treatment will cause the failure of the tool. In the tool-manufacturing industry today, accurate control of the many heating operations is imperative. The principal processes in the manufacture of tools that require accurate high-temperature measurements are annealing, carburizing, hardening, tempering, and laboratory research. Several other operations, such as forging and straightening, use rougher and correspondingly less accurate methods. These operations are usually performed in the following approximate ranges of temperature: DEGREES F. DEGREES F. Annealing 1000 to 1700 Tempering 200 to 1200 Carburizing 1400 to 1000 Forging 1400 to 1800 Hardening 1400 to 2500 Straightening 300 to 1300 Laboratory research covers the entire range. Annealing and carburizing are usually done in muffle or semi-muffle furnaces, heated with coal, coke, oil, gas, or electricity. Many of them are of large size, holding several tons of steel at one charge. Both indicating and recording pyrometers are used. The recording instruments are generally of the thermoelectric type, while for the indicating, both optical and thermoelectric are used.

Jan 9, 1919

By Carroll F. Hardy

THE position of the coal industry has been affected by a wide variety of developments in the production and use of energy. The tempo of development and change has been increasing and the end is not in sight. Legislation is currently being proposed for commercial use of atomic power, and the employment of atomic energy in significant quantity will probably occur about the same time as the decline in production of petroleum and natural gas. But these developments are in the future and have little immediate effect on utilization and marketing of coal. While no one should try to suppress or retard the development of a new and economical source of energy, both the coal and private utility industry should be allowed to question how the nuclear power is to be used, who is to use it, and who is going to pay for it. The taxpayers have a monopoly on fissionable material and the knowledge to employ it. Any commercial use must stem from this source. It is not hard to visualize either taxpayer- subsidized private utility atomic power plants on one hand and super TVA's on the other. In view of the gains of gas and oil in the home heating field, it is interesting to compare the 1940 and 1950 census reports on the kind of fuel used for heating in occupied dwelling units. Table I shows that whereas coal provided 77 pct of the fuel for central heating (furnaces and boilers) in 1940, it was down to 45.4 pct in 1950. However, only about 1 ½ million units were lost in this 10-year period.

Jan 3, 1954

By S. F. Shaw

THE principles involved in lifting oil in wells flowing naturally are identical with those underlying the flowing of wells by means of the air-gas lift, and information of a dependable nature obtained in the study of the air-lift can be applied to wells with natural flow. A well flowing naturally is one in which the lifting is done by means of the gas-lift, for which the gas is supplied entirely by the formation from which the oil is derived. In air-gas lift operations, there is insufficient gas supplied by the formation to lift the oil to the surface in an efficient manner, therefore additional gas for this purpose must be furnished from an outside source. There may, at times, be conditions obtaining in natural flowing wells different from those in wells flowed by gas-lift, but these differences do not at all conflict with the main principles of gas-lift work. One such condition is met with in wells in which the gas supplied by the formation is in considerable excess of that required to lift the oil to surface; this excess may be so great as to reduce the quantity of oil that can be lifted through the particular diameter of casing or tubing that has been lowered into the well. This same condition can be brought about, however, by supplying a large excess of gas from an outside source to an artificial gas-lift well, and a study of the effects obtained from injecting a large excess into the well can be applied directly to handling wells flowing naturally which have a large excess of gas supplied by the underground reservoir.

Jan 1, 1929

Map

Jan 1, 1957

By A. F. Giamei, E. J. Freise

A discussion of the various factors affecting the accuracy of volume fraction determination by the direct comparison X-ray diffraction method is presented. To minimize errors introduced by nonrandomization effects such as preferred orientation and large grain size, as well as errors introduced by statistical effects, an iterative mathematical analysis is introduced. This analysis is applied to all observable diffractio~ spectra from a given specimen by means of computer techniques and is statistically superior to the standard direct comparison technique which utilizes only one or tm sets of intensity spectra. The computer program also presents a graphical interpretation of- the results which enables the investigator to visualize and readily assess the scatter in volume fraction estimates caused by deviations from randomness. Finally, the iterative analysis is applied to experimental data collected from a series of plain carbon steels in both the as-received and spheroidized conditions to determine the volume fraction of cemen-tite present in each case. The results show markedly good agreement with chemical analyses for all spheroidized specimens. In theory, quantitative X-ray diffraction is a power-ful analytical technique for precise determination of the volume fractions of various phases present in a multiphase poly crystalline aggregate. There are two generally used methods; both utilize the fact that the intensity of a diffraction line of a particular phase is a function of volume fraction of that phase present in the aggregate. The more common method is the so-called internal standard technique where a known amount of standard substance is mixed with the aggregate containing the unknown. The resulting ratio of the intensity of a particular diffraction line of the unknown to the intensity of a diffraction line from the standard is used to find the weight fraction of unknown material by reference to the intensity data obtained from a previously prepared set of standards containing the same amount of standard material. The details of this technique are outlined in standard works on X-ray diffraction.' The disadvantages of the technique are that it requires the use of powder specimens and that the powder mixture must be homogeneous near the surface to the maximum effective beam depth. The alternative technique is the direct comparison method in which the ratio of the intensity of a diffraction line of a phase in the aggregate to the intensity of a second-phase diffraction line yields the ratio of the volume fractions of each phase present. This method has been applied most extensively to the determination of the percentage of retained austenite in martensitic steels and to determining the amounts of hcp and fcc allotropic modifications in pure cobalt5 and the amounts of hexagonal and rhombohedra1 modifications in graphite.8 This method is applicable to bulk as well as powder aggregates and is the technique which will be considered in the following text. It is the purpose of the present communication to show that by combining the results of X-ray diffrac-tometry with the use of high-speed digital computers the results of the direct comparison quantitative X-ray analysis technique can be optimized by using all of the data available on a diffraction pattern. THEORETICAL DISCUSSION In optimizing any quantitative X-ray diffraction experiment, the problem of accuracy vs time to collect and analyze the experimental data arises. For any method to be practical, it is required that both experimental and analytical procedures are reasonably short. In most of the previous work performed by the direct comparison method, intensity data from only one or two sets of peaks were used to calculate the volume fraction of phases present in the aggregate. Consequently, rather long-time experimental measurements are required to assure that the intensity data are sufficiently accurate to justify the use of one or two sets of data. By using computer techniques to analyze the experimental data it becomes feasible to use all of the available data on a diffraction pattern. By so doing, the time spent in measuring any one diffraction maxima can be appreciably reduced. Although this results in poor counting statistics for any one maxima, the number of data points available for analysis is greatly increased. Based on the above discussion, it will be assumed that a continuous scanning counter-diffractometer technique will be used to collect intensity data from a two-phase mixture. The integrated intensity of the ith diffraction line from the a phase in the aggregate is given by:'" where is the volume fraction of the a phase, The various quantities in Eq. [la] are angular independent while those in [lb] depend on the hkl spectrum of a particular phase. The meaning of the individual quantities in Eqs. [la] and [lb] are given in Appendix 1. It is convenient at this point to outline briefly the factors which will affect the measured intensity of any one hkl spectrum. a) Extinction effects arise from two independent experimental conditions. Primary extinction arises from a high degree of crystal perfection and results in spectra having lower intensity than predicted by Eq. [I]. Any treatment, such as powdering, which reduces

Jan 1, 1968