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By Walter Kauzmann

All viscous or plastic flow of incompressible matter is the result of shear strain; the changing shape of any body that is being plastically deformed can be completely described in terms of the shear strain occurring at each point in the body.† Furthermore, the relative amounts of shear strain occurring in different parts of a body under stress depend upon the relative rates of shear strain at those different points, so that if the dependence of the shear rate of any material on the temperature, shear stress, previous history, etc., were understood, the principles of plastic deformation would be known, and we could calculate how a body made of a given material, having a given shape, and subject to a specified system of forces, would change its shape with time. It may be said, then, that the problem of plasticity resolves itself into, first, the problem of the rates of pure shear processes, and second, the application of what is known about pure shear to actual cases. It is the purpose of this work to investigate the former problem —i.e., the dependence of shear rates on temperature, stress, etc.—from the standpoint of .recent developments in the field of chemical-rate theory and with particular reference to the phenomena occurring in the creep of metals and in the plastic flow of crystalline solids in general. It is left for the mechanical engineer, and perhaps the expert in hydrodynamics, to deal with the problem of app1ications.l Resolution of Macroscopic Shear into Microscopic Movements; Resemblance to Chemical Reactions Just as any large body is made up of many small units, or atoms, so macro-scopically observable shear is the result of many microscopic unit shear processes; just as the understanding of the behavior of large bodies demands the understanding of the atoms of which it is made, so the understanding of macroscopic shear demands the understanding of these fundamental unit processes. The study of shear from this "atomistic" point of view has made considerable progress. There has been fairly complete understanding of shear processes in gases for a long time, at least for non-turbulent flow, as a chapter on gaseous viscosity in any text on the kinetic theory of gases will prove' In recent years Andrade2 and Eyring3 have presented important theories for the flow of liquids and amorphous solids. Becker14 Orowan,5 Taylor,6 Burgers,7 and Kanter8 have considered the plastic flow of crystalline solids from this

Jan 1, 1941

By Walter Kauzmann

All viscous or plastic flow of incompressible matter is the result of shear strain; the changing shape of any body that is being plastically deformed can be completely described in terms of the shear strain occurring at each point in the body.† Furthermore, the relative amounts of shear strain occurring in different parts of a body under stress depend upon the relative rates of shear strain at those different points, so that if the dependence of the shear rate of any material on the temperature, shear stress, previous history, etc., were understood, the principles of plastic deformation would be known, and we could calculate how a body made of a given material, having a given shape, and subject to a specified system of forces, would change its shape with time. It may be said, then, that the problem of plasticity resolves itself into, first, the problem of the rates of pure shear processes, and second, the application of what is known about pure shear to actual cases. It is the purpose of this work to investigate the former problem —i.e., the dependence of shear rates on temperature, stress, etc.—from the standpoint of .recent developments in the field of chemical-rate theory and with particular reference to the phenomena occurring in the creep of metals and in the plastic flow of crystalline solids in general. It is left for the mechanical engineer, and perhaps the expert in hydrodynamics, to deal with the problem of app1ications.l Resolution of Macroscopic Shear into Microscopic Movements; Resemblance to Chemical Reactions Just as any large body is made up of many small units, or atoms, so macro-scopically observable shear is the result of many microscopic unit shear processes; just as the understanding of the behavior of large bodies demands the understanding of the atoms of which it is made, so the understanding of macroscopic shear demands the understanding of these fundamental unit processes. The study of shear from this "atomistic" point of view has made considerable progress. There has been fairly complete understanding of shear processes in gases for a long time, at least for non-turbulent flow, as a chapter on gaseous viscosity in any text on the kinetic theory of gases will prove' In recent years Andrade2 and Eyring3 have presented important theories for the flow of liquids and amorphous solids. Becker14 Orowan,5 Taylor,6 Burgers,7 and Kanter8 have considered the plastic flow of crystalline solids from this

Jan 1, 1941

The first record of coal anywhere in the Appalachian regions of which we now know is along the north fork of the Potomac River, above the mouth of Savage River, on a map entitled, A Plan of the upper Part of Potomack River call Cohongorooto Survey'd in the Year 1736. Benj. Winslow1 two "Cole-mines" are shown, one just above Green Island and the other just below Hopwood Run. Winslow was in charge of a surveying party to "Lay out the Bounds of the Northern Neck of Virginia," or Lord Fairfax's Grant, his party locating the liver above the mouth of the Shenandoah, while another party located it below that point, and then around Chesapeake Bay and up the Rappahannock River. The results of the two surveys were combined in a map called, The Courses of the Rivers Rappahannock and Potowmack, in Virginia, as surveyed according to Order in the Years 1736 & 1737, made by Wm. Mayo, which does not show the "cole-mines;" this map was used with the report of the boundary commission which was sent to London in the case before the Privy Council. The boundary line decided upon was surveyed on the ground in 1746, just ten years after the original one. The results of this work were shown on A Map of the Northern Neck in Virginia, According to an Actual Survey begun in the Year MDCCXXXVI, and ended in the Year MDCCXLVI, Drawn by Peter Jefferson And Robert Brooke, Surveyors, which is now in the Colonial Office in London. This map shows the "cole-mines" in the same location as on Winslow's map, and taken from his record, of course, as that part of the survey was not retraced. Faulkner, who examined all of these records in his review of the case in 1832, refers to the notes of the original survey as "No. 10. The original field notes of the survey of the Potomac River, and the mouth of the Shenandoah to the head spring of said Poto¬mac River, by Mr. Benjamin Winslow." While the notes of the 1746 survey are in the London records and photographic copies of them are in several libraries in this county, the notes of the 1736 survey cannot be found anywhere. (For Chas. J. Faulkner's report, dated Nov. 6, 1832, see Kercheval's History of the Valley of Virginia, pp. 160-173. Jas. W. Foster's Maps of the First Survey of the Potomac River, 1736-37, in Wm. and Mary College Quarterly History Mag., April, 1938, gives a complete history

Jan 1, 1942

By Gerhard Derge

Metallurgists have used borax as a fluxing agent traditionally, but until recently elemental boron has played an insignificant role as an alloying element. Neither the metal nor its compounds have been regarded as important metallurgical materials and there is a surprising lack of knowledge concerning their metallurgical behavior. The new applications to steel-making of both boron and borates, which arose in part from wartime incentives and restrictions, have been seriously handicapped by this lack of data. For example, rasorite, a naturally occurring sodium borate, has been shown to be an effective substitute for aluminum as a ladle deoxi-dizer in rimming steels.' Likewise, the effectiveness of boron as an alloying agent has been demonstrated,2,3 giving deep hardening when used in restricted amounts. The exploitation of both of these uses has been retarded by the difficulty of attaining suitable metallurgical control. Recognizing that the most important information required was a knowledge of the equilibrium between boron and oxygen dissolved in liquid iron. Gurry4 calculated this relation from the best thermal data available. However, estimates of the entropy of melting of boron, the activity coefficient of boron in liquid iron and the activity coefficient of B2O3 in slag were involved, and experimental work on this problem was obviously desirable. The experiments to be described were planned to establish the boron-oxygen relations in liquid iron and to demonstrate at the same time the ferroborate slag compositions in equilibrium with various amounts of oxygen in liquid iron. Accordingly, slags containing varying proportions of iron and boron oxides were held in contact with molten iron, and samples of both slag and metal were analyzed. The limitations upon the accuracy of the data will be considered, but in a practical sense the oxygen levels that can be attained in iron by iron borate slags, and the amounts of boron in iron at these oxygen levels were established. Experimental Procedure No entirely suitable refractory was found for the mixtures of iron oxide and boron oxide used as slags. Crucibles of silica, magnesia, Ramix, beryllia, and zirconia were all tried unsuccessfully. The must satisfactory method discovered for handling them was the rotating-crucible technique, which creates a parabolic crucible of liquid iron.5,6 Even this was not entirely successful, for at steelmaking temperatures (1600°C.) the slags had such a low surface tension that they crept up to the refractory and slowly dissolved it. These difficulties made it impossible to maintain a constant slag composition for an unlimited period Of time. However, by using the rotating technique, short runs could be made in

Jan 1, 1947

By Gerhard Derge

Metallurgists have used borax as a fluxing agent traditionally, but until recently elemental boron has played an insignificant role as an alloying element. Neither the metal nor its compounds have been regarded as important metallurgical materials and there is a surprising lack of knowledge concerning their metallurgical behavior. The new applications to steel-making of both boron and borates, which arose in part from wartime incentives and restrictions, have been seriously handicapped by this lack of data. For example, rasorite, a naturally occurring sodium borate, has been shown to be an effective substitute for aluminum as a ladle deoxi-dizer in rimming steels.' Likewise, the effectiveness of boron as an alloying agent has been demonstrated,2,3 giving deep hardening when used in restricted amounts. The exploitation of both of these uses has been retarded by the difficulty of attaining suitable metallurgical control. Recognizing that the most important information required was a knowledge of the equilibrium between boron and oxygen dissolved in liquid iron. Gurry4 calculated this relation from the best thermal data available. However, estimates of the entropy of melting of boron, the activity coefficient of boron in liquid iron and the activity coefficient of B2O3 in slag were involved, and experimental work on this problem was obviously desirable. The experiments to be described were planned to establish the boron-oxygen relations in liquid iron and to demonstrate at the same time the ferroborate slag compositions in equilibrium with various amounts of oxygen in liquid iron. Accordingly, slags containing varying proportions of iron and boron oxides were held in contact with molten iron, and samples of both slag and metal were analyzed. The limitations upon the accuracy of the data will be considered, but in a practical sense the oxygen levels that can be attained in iron by iron borate slags, and the amounts of boron in iron at these oxygen levels were established. Experimental Procedure No entirely suitable refractory was found for the mixtures of iron oxide and boron oxide used as slags. Crucibles of silica, magnesia, Ramix, beryllia, and zirconia were all tried unsuccessfully. The must satisfactory method discovered for handling them was the rotating-crucible technique, which creates a parabolic crucible of liquid iron.5,6 Even this was not entirely successful, for at steelmaking temperatures (1600°C.) the slags had such a low surface tension that they crept up to the refractory and slowly dissolved it. These difficulties made it impossible to maintain a constant slag composition for an unlimited period Of time. However, by using the rotating technique, short runs could be made in

Jan 1, 1947

By Herbert H. Kellogg

RECENTLY the long-chain primary amines have been used extensively for the flotation of silicate minerals. The use of amines to float sulphide minerals has been investigated by several authors1-5,18 but most of this work has been done with the short-chain (less than six carbon atoms) primary amine compounds or the more expensive secondary, tertiary and quaternary amines. Perhaps the fact that the long-chain amines are good collectors for the common gangue minerals has led investigators to omit them from consideration as collectors for the selective flotation of metallic sulphides. The work reported in this paper was designed to investigate the use of a typical long-chain amine salt, lauryl amine hydrochloride, as a collector for the flotation of galena-sphalerite ores. The results show that lauryl amine hydrochloride (LAmHCI), when used in small amounts, is a good collector for the selective flotation of sphalerite and galena from the common gangue minerals. The differential flotation of sphalerite from galena was not accomplished but the amine flotation of sphalerite after the standard xanthate flotation of galena is possible. The experimental work reported herein is not complete enough to be able to say whether amine flotation of lead-zinc ores would prove superior to xanthate flotation, or whether the method is even applicable to a more complex ore than the one used for this work. However, the apparent reagent costs for the flotation operations described in this paper seem to be less than for xanthate flotation. This fact alone should be sufficient to encourage the millman to investigate the use of these amine reagents, especially as these reagents are available on a commercial scale at a reasonable price. This paper has as its secondary purposes to illustrate how contact-angle measurements have aided in this investigation, and to bring forward some evidence concerning the mechanism of the collecting action of primary amines. CONTACT-ANGLE TESTS The contact-angle measurements were made by the method described by del Giudice6 and used in recent work by Taggart and his collaborators.7-9 The mineral specimens for the contact-angle tests were carefully chosen, to avoid cracks and inclusions of other minerals. All specimens were mounted in "transoptic" plastic mounts and the surfaces were cleaned by polishing with levigated alumina on a cloth-covered glass polishing wheel. Distilled water was used on the lap during the polishing and at all subsequent steps in the contact-angle tests. The mounted mineral specimens were handled with glass forceps and special care was exercised to prevent exposure of the dean surface to air or any other source of contamination.

Jan 1, 1945

By D. E. Etter, J. E. Selle

The Pu-Ce phase diagram was determined by differential thermal analysis, metallography, and elechm-nricroprobe analysis. The dingram is chararterized by a eutectic with extensive solid solubility in the cubic Phases of both cerium and plutonium. No intermediate phases were found. Cerium is soluble in e plutonium to 16.0 at. pet Ce at 626OC nnd in d plcltoniurn to 23.0 at. pet at 613 "C, decreasing to 17.5 at. pet at room temperature. No solubility in the a, ß, or ? phases was jound, and the mininum cerium required to stabilize 5 plutonium to room temperature is 3.2 at. pet. The maximum solubility of plutonium in 6 cerium is 19.5 at. pet at 721OC, and the maximum soluhility of plutonium in ? cerium is 34.5 at. pet. Invariant points in the system are: a) eutectic at 626oC, L16.5 = E Pu16.0 + y Ce65.5; b) peritectoid at613oC, e Pu13.5 -y Ce65.5- d Pu23.0. AS part of a program aimed at the determination of the phase equilibria in the Pu-Ce-Cu ternary system, preliminary investigations were made of the three binary systems. A survey of the Pu-Ce binary system by differential therma1 analysis indi- cated several areas of disagreement with the published diagram,' primarily in the shape of the liquidus surface. Consequently, a thorough investigation of the system was undertaken, and this report presents the results of the study. EXPERIMENTAL PROCEDURE Three methods of investigation were used: differential thermal analysis (DTA), metallography, and analysis with electron-microprobe X-ray analyzer (EMX). The EMX analysis was particularly useful for the determination of solvus lines. The DTA method was most useful for the determination of the liquidus curves. Metallography complemented both of these techniques. Materials. The cerium metal used for most of this work had a freezing point of 805°C. This material showed 15°C premelting, and was found metallographically to contain some unidentified in~lusions.2 The temperature of premelting is defined as the point at which the DTA curve breaks away from the base line, analogous to a curve obtained from a solid-solution alloy. Several compositions were prepared near the cerium end of the diagram with higher-purity material which had a freezing point of 800°C. etallographic analysis showed this material to be relatively free of inclusions and only 8°C premelting was observed. Major impurities were found by spectrographic

Jan 1, 1964

By R. H. Fillnow, D. J. Mac

IT has been demonstrated that alloys in systems structurally analogous to steel undergo reactions during heat treatment similar to those of steel, and yet very little work has been done on such systems, particularly from the standpoint of isothermal transformation. The literature shows that most of the isothermal work has been done on copper-alu-minum alloys.'-3 One paper has been reported on a eutectoid copper-silicon alloy,' and one on iron-nitrogen alloys.' There are no published reports of previous investigations on the isothermal transformation of a eutectoid beryllium bronze. At least two papers have been reported on isothermal age-hardening phenomena in beryllium-copper alloys of lower beryllium content.5,6 No information on eutectoid transformations in this alloy is given in Rimbach's book, "Beryllium." ' This paper reports the results of an investigation on the isothermal transformation characteristics of a eutectoid beryllium bronze. Materials Used and Procedure The eutectoid beryllium bronze used in this investigation was centrifugally cast at the Ampco Metal Co., Inc.. Milwaukee. Wis. A master beryl-lium-copier alloy, purchased from the Brush Beryllium Co., was used to make the beryllium addition to the copper. The alloy was melted under a protective carbon cover and Centrifugally cast into a graphite mold preheated to 920°F. Some trouble with segregation of beryllium in the melt was encountered but was eliminated by violent stirring during melting and pouring. Since very thin .specimens were used for the various heat treatments, only one casting of the four prepared was necessary for the complete isothermal study, thus eliminating any discrepancies caused by a change in composition. The analysis of this casting was 94.035 pct copper and 5.965 pct beryllium. A slight trace of iron was found. The castings were sawed into specimens approximately 3/32 in. in thickness. The specimens were first given an "austenitizing" heat treatment at 788°C, well within the single phase beta region, in a vertical tube furnace. The specimens were then quenched individually into an adjacent molten salt bath and held there for a definite time, after which they were quenched into water at room temperature. Temperature was held to ± 2°C in the salt bath. No homogenizing treatment was given the specimens other than the soak at 788°C. Despite the fact that this was a cast alloy, no evidence of segregation or coring was found in the microstructure of any specimen, either as cast or as heat-treated. Upon completion of the heat treatment, the speci-mens were subjected to metallographic examination

Jan 1, 1951

By C. E. Nelson, T. E. Leontis

THE properties and casting characteristics of sand-cast Mg-Al-Zn alloys, used commercially in this country and abroad, have been discussed in a number of articles during the past few years.'-" In addition, broad surveys of many compositions in the magnesium corner of the Mg-Al-Zn diagram between 0 and 12 pct A1 and 0 and 6 pct Zn have been presented by Busk and Marande7 and by Fox." The purpose of this paper is to furnish a comprehensive survey of the changes in tensile properties, micro-structure, and dimensional stability of two magnesium alloys, AZ92A and AZ63A,+ as a function of aging time and temperature after solution heat treatment. Rates of precipitation in Mg-Al-Zn alloys are slow enough so that a substantially homogeneous, supersaturated solid solution can be maintained even when these alloys are air-cooled from the heat-treating temperature. Consequently, even though it has been demonstrated9 10 that significantly higher strengths can be developed in some alloys in the aged condition by quenching rather than air cooling from the heat-treating temperature, general practice is to air-cool magnesium alloys. All the work discussed in this paper is based, therefore, on aging studies performed on material air-cooled from the heat-treating temperature. This investigation was intended to be a study of commercially practical aging cycles; the tensile properties were determined, therefore, up to aging times of 25-hr duration. The alloys, used in this investigation were prepared in the laboratory by remelting commercial ingots of the appropriate composition according to the procedures described in a previous paper" as the "crucible method." All melts were given the standard superheating treatment in order to insure the maintenance of a uniform grain size of 0.003 to 0.004 in. Standard test bars, 61/2 in. long with a 2½ in. long reduced section having a diameter of Y2 in., were cast from these melts in green-sand molds using a four-bar pattern. The alloys were heat treated according to the following schedules: AZ92A alloy: 500" to 780°F in 2 hr + 780°F (24 hr) AZ63Aalloy: 500" to740°Fin2 hr + 740°F (16hr) In commercial practice," AZ92A alloy is heat treated at 770°F for 18 hr and AZ63A alloy is heat treated at 730°F for 10 hr. The slightly higher temperatures and longer periods of heat treatment were used in order to obtain as homogeneous a solid solution as possible and thus to minimize inconsistencies in the

Jan 1, 1952

By H. Cecil Spicer

The results described in this article are based on field work conducted during the periods APril-May, 1939, and MaY-JulY, 1940. The United States Potash CO. is mining potash on Government land under a permit from the Department of the Interior and the geophysical investigation mas completed under a cooperative arrangemerit made between that company and the Conservation Branch of the Geological Survey. The writer, a member of the Section of Chemistry and Physics of the Geologic Branch, was assigned to this investigation. Four definite objectives were in mind for the geophysical work in the studies over the salt deposits. The first was to determine the measure of success that could be attained in this type of work with the resistivity methods that were to be employed. These methods had been introduced into the work of the Conservation Branch by Benjamin E. Jones for the investigation of dam sites, and have been used under his direction by the author for such work. If the method proved to be applicable, an l was to be made to contour the top of the salt beds and also the other formation boundaries known to be present in this area. Salt-water aquifers were to be studied in an effort to determine their boundaries, and an attempt was to be made to delineate the potash-bearing beds. Others have made, and reported, resistivity studies over saliferous deposits in different areas. Friedell and Messrs. Schlumberger2 reported geophysical work performed in the disrovery of the salt domes of Alsace; Carrette and Kelly3 described the geology of the same area. Leonardon and Kelly4 published a resistivity curve obtained over the Hettenschlag dome, and a further discussion of this same area was given by the Messrs. Schlum-berger5 in a communication. Messrs. Alty6 described studies 0" salt deposits in which the sing[e-probe method was used. Sinerez7 mentions that electrical methods were tried over salt deposits in Spain. Geoffrey and Charrin8 show a resistivity curve obtained over marl, gypsiferous marl and salt which is similar to that obtained over the New Mexico salt deposits. Kelly9 reported resistivity work performetl with the ground comparator of Zuschlag over the salt deposits near Syracuse, N. Y., where the Salina formation is at a depth of 700 to 800 ft. Some structural studies on the potash basin of Alsace are described by Poldini.10 Another single-probe resistivity study, made over salt deposits in New Mexico, is briefly described by Heiland,ll through the courtesy of Harry Aurand, of the Midwest Refining CO.

Jan 1, 1942

By H. Cecil Spicer

The results described in this article are based on field work conducted during the periods APril-May, 1939, and MaY-JulY, 1940. The United States Potash CO. is mining potash on Government land under a permit from the Department of the Interior and the geophysical investigation mas completed under a cooperative arrangemerit made between that company and the Conservation Branch of the Geological Survey. The writer, a member of the Section of Chemistry and Physics of the Geologic Branch, was assigned to this investigation. Four definite objectives were in mind for the geophysical work in the studies over the salt deposits. The first was to determine the measure of success that could be attained in this type of work with the resistivity methods that were to be employed. These methods had been introduced into the work of the Conservation Branch by Benjamin E. Jones for the investigation of dam sites, and have been used under his direction by the author for such work. If the method proved to be applicable, an l was to be made to contour the top of the salt beds and also the other formation boundaries known to be present in this area. Salt-water aquifers were to be studied in an effort to determine their boundaries, and an attempt was to be made to delineate the potash-bearing beds. Others have made, and reported, resistivity studies over saliferous deposits in different areas. Friedell and Messrs. Schlumberger2 reported geophysical work performed in the disrovery of the salt domes of Alsace; Carrette and Kelly3 described the geology of the same area. Leonardon and Kelly4 published a resistivity curve obtained over the Hettenschlag dome, and a further discussion of this same area was given by the Messrs. Schlum-berger5 in a communication. Messrs. Alty6 described studies 0" salt deposits in which the sing[e-probe method was used. Sinerez7 mentions that electrical methods were tried over salt deposits in Spain. Geoffrey and Charrin8 show a resistivity curve obtained over marl, gypsiferous marl and salt which is similar to that obtained over the New Mexico salt deposits. Kelly9 reported resistivity work performetl with the ground comparator of Zuschlag over the salt deposits near Syracuse, N. Y., where the Salina formation is at a depth of 700 to 800 ft. Some structural studies on the potash basin of Alsace are described by Poldini.10 Another single-probe resistivity study, made over salt deposits in New Mexico, is briefly described by Heiland,ll through the courtesy of Harry Aurand, of the Midwest Refining CO.

Jan 1, 1942

By Louis S. Cates

At the annual meeting of the American Institute of Mining and Metallurgical Engineers in February, 1923, the Chairman of the Committee on Ground Movement and Subsidence appointed a sub-committee to work out a form of questionnaire and to collect data on subsidence and ground movement resulting from underground metal and coal-mining operations, and on ground movement and safe slopes in connection with open-cut metal-mining operations. The author was requested to take charge of the collection of data and the preparation of a questionnaire in connection with the Committee's studies of open-cut metal-mining operations. This paper is a summary of the work carried on and information received therefrom up to February, 1924. The first approach to the problem of safe slopes is to gather all information that pertains to finished slopes; in other words, the steepest economic angle from the horizontal that will stand in order to uncover the ores to be mined and be safe while the extraction of the ore at the base of these slopes is in progress. Whether or not this angle is 35" or 45" depends on many factors. The number of benches maintained to take care of falling rock and their height and width are direct functions of this overall slope. The slope is here taken to mean the angle from the top edge of the pit through the edges of the respective lower benches to the bottom of the pit. If we accept this definition of the slope, it might save some confusion as there would be a difference if one took the line from the top edge of excavation to the toe of the bottom slope. This latter slope would not be constant, but would vary with the number of benches. The depth of the various ore faces will vary, of course, depending on the deposit; Table 1 shows this to range from 50 ft. to 1100 ft. The geology is an important factor, as are the climatic conditions under which one is operating. A saturated condition in some rock structure causes rock flows; in the Panama Canal excavation, slides have run on a ratio of as low as one on ten, which is a 10 per cent. grade, or a slope of less than 6' with the horizontal. Slopes as steep as 60' have been noted in the Utah Copper operations, so that a wide divergence will possibly be met. The work of securing data that will be of value to the operator or estimating engineer will be difficult and will mean little unless a detailed

Jan 1, 1927

By J. P. Hirth, C. S. Hartley

A simple graphical technique is presented for rapidly determining the ratio of resolved shear stress on slip systems in single crystals to the applied stress (Schmid factor) for various simple states of stress. Master plots are presented which, when used in conjunction with an appropriate stereo-graphic projection, allow one to determine the Schmid factor for all slip systems in a crystal of given orientation. It is shown that one such plot suffices for simple tension or compression, flex-ural bending, and biaxial compression, while a combination of two different plots must be used for torsion and simple shear. STUDIES of the deformation behavior of single crystals are most valuable when the applied stresses are resolved onto the various slip systems of the crystal. A careful study of the available slip systems and proper selection of the state of stress used and the specimen orientation can then yield quantitative information about the probability of specific dislocation reactions, the strength of barriers to plastic flow, and the mechanisms of yielding and flow in general. It is the purpose of this work to analyze some common states of stress used in deformation studies and to present a simplified way of determining for these cases the ratio of the resolved shear stress on the slip systems to the applied stress (Schmid factor). I) CALCULATIONS We first define two orthogonal coordinate systems: one based on the specimen geometry (a right circular cylinder of radius, R, is considered here) and one based on the particular slip system of interest. The unit vectors and angles specifying the two coordinate systems and the relationship between them are listed in Table I. The relationships among the various angles and unit vectors are shown on a stereographic projection in Fig. 1. The transformation matrix between the (XI X2 X3) and (x'1 x'2 x'3) system is x1 x2 x3 X'1 a11 al2 a13 x'2 a21 a22 a23 x'9 a31 a32 a33 where in this case the direction cosines aij are given by a11 a12 a13 aij = a21 a22 a23 a31 a32 a33 sin 0 cos F cos 0 sin F cos 9 = -cos 0 cos F sin 0 sin F sin 6 [1] 0 -sin F cos (p In terms of Eq. [I.], the stresses sij, referred to the slip system, are determined from oij, referred to the specimen axes, by1,2

Jan 1, 1965

By H. L. Riley, B. W. Gandrud

A froth flotation unit was added to the DeBardeleben Coal Corporation's Empire washer at Empire, Alabama, in the fall Of I94O following an investigation of possible ways and means of recovering coal values from settling-tank overflow or slurry. Officials of the DeBardeleben corporation hoped that some practical and reasonably economical way could be found for recovering fine coal from overflow water, although there had as yet been very little progress along this line in the Alabama coal fields. The Bureau of Mines was asked to cooperate in the project through its Southern Experiment Station, at University, Alabama. This paper presents a brief description of the process and the installation that resulted from the investigation of the overflow water or slurry problem at the Empire mine. The experimental data include' as a Part of this Paper were obtained during the course of the investigation in 1940 Since that time, however, the flotation unit has been running more or less continuously without significant operational changes and is still Performing pretty much in accordance with the data obtained in 1940. Flowsheet at Empire and Type of Coal Treated The Empire mine is developed on the Black Creek bed near the the border of the Warrior field. The coal in this bed is extremely low-ash and although there is an almost complete absence of bone coal and partings, the bed is so thin that, with mechanized mining, a high percentage of rock from roof and floor inevitably gets into the run-of-mine coal. The thickness of the Black Creek bed throughout the part of the Warrior field in which it is mined extensively is rarely over 30 in. and probably would average about 25 in, the coal is of the high-volatile A rank and of excellent quality, but as a result of admixture of roof and floor material, the run-of-mine product usually contains I ; to 20 pct rock by weight. he following is a proximate analysis on an "as-received " basis of a typical seam sample from the Empire mine:' moisture, 3.0 pet; volatile, 34.6 fixed carbon 58.3; ash, 4.1 This sample shelved 15,070 Btu per pound and 0.9 pct sulphur on a moisture-and-ash-free basis. In the Empire preparation plant the lump sizes above 3 in. are removed and hand-picked on a Marcus conveying Screen, the 3 to ? -in. size is removed by vibrating screens and washed in two Montgomery single-cell jigs, and the ?-in. to o slack is cleaned on four diagonal

Jan 1, 1949

By G. L. Boxer, C. B. Smith, W. J. Atkinson

Since the inception of the Ashton (formerly Kalumburu) Joint Venture in 1972 the parties have expended $24 million in exploration for diamonds in the Kimberley region. This has resulted in the discovery of the currently subeconomic Ellendale deposits in 1976/77 and the economic Argyle - Smoke Creek Deposits in 1979/80. In addition to Argyle and Ellendale, some 90 kimberlitic and lamproitic bodies have been discovered grouped broadly into three provinces, on the west, east and north margins of the Kimberley block. These bodies range in size from dyke-like features less than 1 m (3 ft) in width to pipes with a surface area of 128 ha (316 acres). The bodies with larger surface area are volcanic crater deposits, infilled with air-fall and water deposited tuffs and epiclastic sediments. Diamond content ranges from trace to economic concentrations. The exploration discoveries were facilitated by early recognition that the petrography, mineralogy and chemistry of the diatremes varied from the classical kimberlites of Kimberley, South Africa, to unusual more highly fractionated, alkaline, silicic varieties having affinities with leucite-lamproite. Indirect methods of exploration were used, primary reconnaissance work being stream gravel sampling for kimberlitic indicator minerals. Evaluation showed Ellendale diamonds are 90% gem and near gem, but the low grades and tonnage render the deposits unpayable at today's diamond prices. After discovery in late 1979 and completion of a feasibility study by the end of 1982, evaluation studies proved Argyle to be economic. Alluvial diamond mining commenced in 1983 producing 6.2 million carats (Mct) that year, 60% being of industrial quality. Open-pit mining of the AK1 lamproite should start in 198511986 at a rate of 3 million t/a (33 million stpy) and produce 25 Mct/a, making this mine, and Australia, the world's largest producer of diamonds by weight. The revenue from diamond deposits is a function of the grade and the value of the diamonds. The grade is the product of the frequency of occurrence of the diamonds (stone density) and the mean stone size; the value of the stones is strongly related to their size distribution. During evaluation of the West Australian deposits, the diamond distribution was found to vary markedly in stone density and stone size. These variations corresponded with changes in the rock type hosting the mineralization. As a consequence, geological mapping of individual lamproites within the multiple vents and careful monitoring of the diamond distribution became an important part of the evaluation work. Similar variations in stone size and frequency were found to accord with separate alluvial terraces and fan gravels derived by erosion from the Argyle AK1 lamproite.

Jan 1, 1985

By Yves Dardel

INTRODUCTION SINCE the first determination of Dumas1 in 1880, many authors have tried to measure the solubility of hydrogen in solid aluminum, or at least the amount of dissolved gas in it. However, the interpretation of the results which have been obtained is still difficult. Sieverts,2 then Baukloh and Oesterlen,3 during their gassing experiments could not determine any solubility of hydrogen in solid aluminum. On the other hand, Portevin, Chaudron and Moreau,4 leaving the determination of the hydrogen solubility beyond the scope of their experiments, measured only the amount of gas that they could extract by high voltage positive ion bombardment and found up to 151 cm3 of gas per 100 g of metal. Winterhager,5 by repeated vacuum extraction during severe cold rolling, extracted up to 161 cm3 per 100 g. In both series of experiments, the extracted gas contained chiefly hydrogen with a small amount of nitrogen, carbon monoxide, carbon dioxide and methan. Later, Schmidt and von Schweinitz6 as well as Chaudron and Moreau7 showed the importance of the adsorbed layer of hydrogen, the extracted quantities being proportional to the surface and not to the weight of the sample, when its cleaning was not perfect. In earlier experiments, Steinhauser8 extracted from more massive samples nothing but a little amount (< 0. 5 cm3 per 100 g) of hydrogen, carbon monoxide and methane. Thus, according to these experiments the quantity of dissolved gas is probably very small and the effect of the surface could falsify the results of the extraction. However, owing to the care taken by Chaudron and his coworkers, it was clear that all the hydrogen extracted could not come from the superficial layer, or that the links which bound hydrogen to the surface were so strong that the usual method of cleaning could not destroy them. After the main parts of the experiments reported here had already been carried out, Eborall and Ransley9 published the results which they obtained with an analysor having an accuracy of 0.03 cm3 per 100 g, while that of the usual apparatus was only about 0.2 cm3 per 100 g. During all their experiments the adsorbed layer would have been a difficulty, for the value of the adsorbed hydrogen was approximately equal to that of the dissolved amount. [ ] Since always keeping the same adsorbed layer is very difficult, an error in the correction for the adsorption can be made when using the apparatus of Eborall and Ransley, as well as the earlier apparatus,

Jan 1, 1948

By Elmars Ence, Harold Margolin

The partial isothermal section of the Ti-Cu-Zr system at 750°C has been studied. The crystal structure of Ti2Cu has been detevnlined as tetragonal and when expressed as face-centered tetragonal, a = 4.164, c = 3.611 A, and c/a = 0.867. TITANIUM systems in which ß-titanium decomposes eutectoidally into a and a compound rather readily are known as active eutectoid systems. Recently in active eutectoid alloys based on the Ti-Cu system, and containing additionally A1 and Zr, it has been found that zirconium may produce both moderate weakening and marked strengthening at elevated temperatures.&apos; In order to obtain some insight into the behavior of zirconium, an attempt was made to determine whether compounds of the type Tix Zr and TixZryCu exist. Only results of the Ti-Zr-Cu studies are reported here since data on Ti-Zr alloys will be presented in a separate publication. EXPERIMENTAL PROCEDURE Alloys were nonconsumably arc melted in argon atmosphere as 15-g buttons, prepared from materials of the following purities: Bureau of Mines electrolytic Ti — Bhn 63 OFHC copper Reactor Grade Zirconium Bhn .C 150 Prior to alloy preparation the electrolytic titanium was premelted to avoid excessive spattering of the charges during melting. The weight losses during melting did not exceed 1 pct of the total weight of the charge. The alloys prepared are listed in Table I together with analyzed compositions. in cases where they were determined. Specimens for heat treatment were wrapped in molybdenum sheet, annealed in argon-filled quartz capsules, and quenched by breaking the capsules under iced brine. About 1 to 2 sec are required to remove the capsule from the furnace, drop it into the iced brine and break it. Because of the insulation effect of the quartz, this delay in quenching should not produce a large drop in temperature. In many instances, no difference or little difference has been detected between the same specimen quartz capsule quenched or directly quenched in vacuum by an impinging stream of water.&apos; Ti-Cu-Zr alloys were homogenized for 48 hr at 825°C prior to annealing at 750°C. Annealing for 5 days at 750°C produced the same results as 11 days at temperature and it was therefore assumed that 5 days was sufficient to establish equilibrium. Titanium-copper alloys were homogenized for 40 hr at 900°C prior to heat treatment for 6 days at 750°C. Specimens for metallographic examination were electropolished and etched with the following solution:

Jan 1, 1962

By Howard Thompson, H. N. Hall, Frank Nuss

Removal of bit cuttings is an important function of drilling muds. In an effort to obtain better understanding of the factors influencing the removal of cuttings, an extensive series of laboratory tests were made in which slip velocities of various sizes and shapes of particles were measured in muds of different physical properties. Empirical equations were then derived from these experimental data. These equations show that slip velocity is dependent on cutting size and shape, mud flow constants, and flow state of the mud. Applicability of these equations for field use is demonstrated by comparing computed slip velocities with slip velocities obtained from field tests. Drilling muds have many functions, but perhaps the most important is the removal of bit cuttings from the well. In a 10,000-ft well, the weight of rock which is drilled and must be carried to the surface is over 150 tons. In addition to this, the mud must remove any sloughings from the well bore. Failure of the mud to promptly remove either bit cuttings or sloughs from the well bore causes re-drilling and excessive wear on bit teeth, slows down drilling rate thereby increasing well costs, and greatly increases possibilities for stuck drill pipe when circulation is stopped for any length of time. Drilling muds lift bit cuttings to the surface by means of the upward velocity of the drilling mud in the annulus. Because a density difference exists between the rock being drilled and the drilling mud, there is a difference between mud velocity and the rate of bit cutting travel, called the net rise velocity. To evaluate the ability of any type of drilling mud in respect to lifting cuttings, some method must be known for predicting the rate of fall of cuttings through mud traveling upwards in the annulus. Equations for the rate of fall of particles through a true fluid have been satisfactorily determined by several authors. 1-6 Since drilling muds are not true fluids, but obey the laws of Bing-ham,7 it should not be expected that equations for rate of fall of cuttings in a true fluid would be applicable to plastic fluids such as drilling muds. Several authors have attempted to compute cutting slip velocities in muds using a viscosity value obtained with a Stormer viscosimeter; however, unsatisfactory results were obtained. Pigott8 took cognizance of the phenomenon of variation of viscosity with velocity in laminar Row, and calculated laminar slip velocities using a variable viscosity with Stokes law, and turbulent slip velocities using Rittingers law. Drilling muds obey the laws of plastic flow which involve factors not affect-

Jan 1, 1950

By Robert A. Colten, Frederick C. Hull, Robert F. Mehl

It is known that pearlite forms from austenite by a process of nucleation and growth, and that the rate of formation of pearlite may be described by a rate of nucleation and a rate of growth.l,2 The manner in which these two quantities operate to produce the observed isothermal reaction curve has been analyzed in a paper published in I939.3 Two types of process were described: (I) that in which nucleation occurs at the grain boundaries of the parent phase, with the nodules growing toward the centers of the grains, initially as hemispheres and then after impingement as roughly radial-columnar structures; and (2) that in which nucleation occurs generally, with the nodules growing to full spheres until impingement with other growing nodules restricts growth. Both cases are met in the formation of pearlite from austenite (Fig. I);2,4 the former, occurring near the knee of the S-curve, has been named "grain-boundary transformation," and the latter, occurring at temperatures near Ael, has been named "group-nodule transformation." In developing our knowledge of the factors that determine the rate of formation of pearlite from austenite, it is important1,2 to obtain data on the rate of nucleation and the rate of growth of pearlite. Such data, when obtained near the knee of the S-curve, will furnish information of use in understanding the factors that affect hardenabil-ity; when obtained at higher temperatures, such data will be useful in understanding the behavior of steels that during heat-treatment react to pearlite.2 It is the purpose of this paper to present data on the rate of nucleation and the rate of growth of pearlite in dependence upon composition, grain size, temperature, and the degree of homogeneity of the parent austenite. The studies are restricted chiefly to plain carbon commercial steels." Previous Data on Rate of nucleation and rate of Growth Data on the rate of nucleation and the rate of growth of pearlite have been published by Scheil and Lange-Weise,5 by Mirkin and Blanter,6,7 by Meh1,l and by Dorn, De Garmo and Flanigan.2, It is difficult to interpret the data, for in most cases too little information is given on austenitizing temperatures and times, the state of homogeneity of the austenite (presence or absence of carbide, etc.), austenite grain size, and mode of formation of pearlite at the temperatures given. Except for the approximations of Mehl and the work of Dorn, austenite grain size was disregarded, though it is well known

Jan 1, 1942

By Robert A. Colten, Frederick C. Hull, Robert F. Mehl

It is known that pearlite forms from austenite by a process of nucleation and growth, and that the rate of formation of pearlite may be described by a rate of nucleation and a rate of growth.l,2 The manner in which these two quantities operate to produce the observed isothermal reaction curve has been analyzed in a paper published in I939.3 Two types of process were described: (I) that in which nucleation occurs at the grain boundaries of the parent phase, with the nodules growing toward the centers of the grains, initially as hemispheres and then after impingement as roughly radial-columnar structures; and (2) that in which nucleation occurs generally, with the nodules growing to full spheres until impingement with other growing nodules restricts growth. Both cases are met in the formation of pearlite from austenite (Fig. I);2,4 the former, occurring near the knee of the S-curve, has been named "grain-boundary transformation," and the latter, occurring at temperatures near Ael, has been named "group-nodule transformation." In developing our knowledge of the factors that determine the rate of formation of pearlite from austenite, it is important1,2 to obtain data on the rate of nucleation and the rate of growth of pearlite. Such data, when obtained near the knee of the S-curve, will furnish information of use in understanding the factors that affect hardenabil-ity; when obtained at higher temperatures, such data will be useful in understanding the behavior of steels that during heat-treatment react to pearlite.2 It is the purpose of this paper to present data on the rate of nucleation and the rate of growth of pearlite in dependence upon composition, grain size, temperature, and the degree of homogeneity of the parent austenite. The studies are restricted chiefly to plain carbon commercial steels." Previous Data on Rate of nucleation and rate of Growth Data on the rate of nucleation and the rate of growth of pearlite have been published by Scheil and Lange-Weise,5 by Mirkin and Blanter,6,7 by Meh1,l and by Dorn, De Garmo and Flanigan.2, It is difficult to interpret the data, for in most cases too little information is given on austenitizing temperatures and times, the state of homogeneity of the austenite (presence or absence of carbide, etc.), austenite grain size, and mode of formation of pearlite at the temperatures given. Except for the approximations of Mehl and the work of Dorn, austenite grain size was disregarded, though it is well known

Jan 1, 1942