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By Edgar S. Cook

Portions of this paper repeat in substance the statements made by me in an address before the meeting of the American Society for Testing Materials, held in June, 1903, at Delaware Water Gap, Pa. The views I then expressed, I still hold and believe to be pertinent to the present discussion of this subject. In doing my part, therefore, at the request of our Secretary, towards the further consideration by the Institute of the Physics of Cast-lron from a commercial as well as a theoretical standpoint,—a theme which received interesting treatment in our meeting some years ago, but has been somewhat neglected recently,—I make no apology for reiterating the views I have expressed elsewhere. Indications all point to the substitution of classifying pig-iron by chemical analysis for the old-time method of grading by fracture. Commencing with the larger users, and the makers of specialties, who require more positive information as to the composition than is afforded by the fracture; the use of pig-iron, guided by analysis, has spread with much greater rapidity to all classes of foundry-work than the most sanguine expected. Grading by fracture, as guided by experience with any particular brand of iron, has some points in its favor. The fact that, for so many years, castings of multitudinous forms, and for an endless variety of uses, were made in a fairly satisfactory

Jan 1, 1905

By C. H. Curtis

The valuable mineral content of the current feed to the Miami concentrator is as follows: copper, 0.7 pct total; molybdenum, 0.01. Flotation of this ore yields a sulphide concentrate containing: chalcocite, 44 pct; molybdenite, 0.5; pyrite, 50.0; insol, 5.5. A combination of potassium ethyl xanthate and pentasol amyl xanthate as collectors, and pine oil as frother, are used in this flotation. Rejection of pyrite is encouraged by holding the amount of collectors used to the minimum consistent with copper recovery and by operating at high alkalinity (equivalent to 0.35-0.40 lb CaO per ton solution of pH 11.0).

Jan 4, 1950

By Emil Gathmann

INTRODUCTION. IN presenting this paper I will attempt to answer certain questions proposed at this meeting and describe and illustrate methods of producing sound steel in an economical and hence commercial manner, which are adaptable to the production of practically all steel manufacturers, by readily effected rational changes in the methods of casting, cooling, and subsequent handling of the ingots. In some of the high-grade mills of America, where it is essential to obtain perfectly sound billets or blooms, it is the practice to discard from 35 to 40 per cent. of the crop- or pipe-end, and even with this excessive discard, secondary pipe or shrinkage-cavities are frequently discovered during subsequent working of the blooms and billets into their various manufactured products. The usual discard of from 10 to 20 per cent. from the crop-end of the ingot, which is made by the present generally employed methods of form and solidifying of the castings, certainly does not give the slightest assurance of the saleable product being physically sound or chemically homogeneous. I am aware that in the past there has been and at the present time there still is a decided difference of expert opinion as to what constitutes physically sound steel.

Jan 4, 1913

By William C. Peters

The pre-production interval, beginning with the recognition of an orebody's best potential and ending with significant production, contains time-dependent conditions well appreciated by miners but not always understood or appreciated by the landowners, investors, and legislators with whom a miner must deal. The expression persists, even outside of Western fiction, that someone has "found a mine." From a slightly more knowledgeable position, the question is asked "How long does it take to make a mine?" and an all-encompassing answer is expected. By scanning the discovery and development history of hundreds of mines and rejecting those which involve rehabilitation or expansion of older mines, some generalizations can be attempted. It should be kept in mind that while physical conditions involving the geology of the orebody and the geographic surroundings do not change markedly with time, technologic and economic conditions do change from year to year. The new methods, facilities, markets, land tenure, and politics form a pattern in which today's mines are made and which do sometimes modify the pre-production interval.

Jan 8, 1966

By R. Varbanov, D. Nikolov, I. Nishkov

An interesting new flotation technique which reportedly improves mineral recovery over an extended particle size range-from 3 mm to 5 microns and below-has been developed by the Institute of Physical Chemistry, Bulgarian Academy of Sciences. Designated the "static" flotation technique, it is suited for upgrading tin, molybdenum, tungsten, uranium, gold, copper, lead, zinc, and other metallic ores. Recoverable nonmetallics include feldspar, sulfur, and phosphorite. Characteristic of the static flotation process are: •longer contact period (up to 1000 times longer between particles and bubbles, •low collision velocity and inertial forces between the contact and aeration in a thin pulp layer, • aeration without the harmful hydrodynamic repulsion upon particles below 5 microns (the pulp layer is only a few millimeters thick and rising bubbles collide with the particles either directly or in the thin foam films formed), •option to conduct the process with or without froth by film flotation at equilibrium contact angles, and • the use of inexpensive frothers and/or unstable froth with separate regulations of froth stability by hydrodynamic, ultrasonic, or electrostatic means.

Jan 10, 1979

By Gerd L. Klinkenborg

Ever see a curvaceous conveyor belt? Reports from Europe indicate appreciable interest in a relatively new system that has revamped some of the concepts of what single-belt conveyors can and cannot do. Invented about ten years ago by two German engineers, the so-called "Serpentix" single-belt conveyor, patented by the firm of Albert Stuebbe, is now operating at more than 100 foreign installations. The system boasts of three unique capabilities-climbing, turning and side discharge of load-which give it, the advantages of a multiple-unit system. The new conveyor needs only one drive station (which may be combined with tensioning), and except for the immediate area of the drive, is capable of conveying loads over a non-linear route. Transfer points are eliminated, and discharge points, which may be located anywhere along the route, may be operated automatically or manually, by direct or remote control.

Jan 1, 1962

By W. F. Baldwin

The timing circuit generally employed in Carter Reservoir Behavior Analyzers consists of a synchronous motor driven cam which actuates a microswitch. A mechanically actuated timer of this type has several inherent disadvantages, among which are the following: 1. The first time interval may not be of uniform length, depending on the exact position of the cam at the conclusion of a previous run. 2. The positioning adjustments on the microswitch lever arms are critical and require periodic readjustment. 3. The mechanical system is subject to wear which will ultimately impair its accuracy. It was therefore considered desirable to devise an alternate method which would eliminate these difficulties without introducing others that would be equally troublesome. This note describes the design of an electronic timing device which has been incorporated in the analyzer constructed by the Field Research Laboratories of Magnolia Petroleum Co. The electronic timer circuit is built around a simple neon glow tube relaxation oscillator, the complete circuit diagram of which is shown in Fig. l. The operation of the circuit is as follows: Condenser C, is charged to the critical firing voltage of the neon glow tube VR-75 by battery B1 through resistors R1 and R2. When the neon glow tube fires, the condenser C, is discharged, The charging cycle then repeats itself,

Jan 1, 1950

By G. A. Vissac

In the presentation which follows, wash-ability curves, such as are commonly used in making studies preliminary to the cleaning of any coal or to the concentration of any mineral, have been reduced in each instance to a single straight line; thus all the most important characteristics of the coal or mineral are represented in a form more advantageous than that in which such data usually are shown. To obtain consistent results, float-and-sink data must be based on a single definite narrow size range, which may be designated "a coal unit." It will be shown that such units, each embodying a different size range, can be grouped to form what may be termed "a composite coal." A three-dimensional presentation will emerge, which will closely identify the coal, illustrate its characteristics in a new manner and explain many obscure facts. Float-and-sink Tests For the preliminary study of any cleaning or concentration problem, or in the control of any operation, float-and-sink tests must be made. The results of these tests are grouped in tabular form and then illustrated in various systems of curves; but if such a graphic representation is to have the utmost practical value, it must offer at least the following advantages: (I) It must be easier to read than the tabular results, and (2) it must be easy to plot, check and interpolate. The first requirement will be attained by reducing the number of curves to a minimum, and the second by some system of representation that will use only straight lines. Of the many washing curves now in use, only the "recovery curve," often known as the "composite curve"—a somewhat misleading term—will be considered; Any point on the recovery curve will show what percentage of weight of clean coal can be recovered when the mineral is washed at a certain specific gravity. As an example, the tests listed below Fig. I are illustrated in the drawing by a curve obtained by plotting (I) as abscissas the ash content of the coal recovered and (2) as ordinates the corresponding percentage of refuse discarded; but, in general practice, instead of writing down that weight, it is customary to set down its complement, which is the corresponding weight of coal recovered. From this curve can be deduced the information necessary for the solution of most practical problems. New Form of Graphic Presentation The resemblance of the recovery curve ill Fig. 1, or, for that matter, the recovery curve obtained in common practice! to a Power curve is apparent. The general equation of such a curve is Y = axn, where n is negative. Taking logarithms: log y = a + n log x. Using a logarithmic scale, the equation of the recovery curve will be Y = A + bX. On this logarithmic basis! the recovery graph will be a straight line, using the same variables as in Fig. I; namely, the ash con-

Jan 1, 1942

By G. A. Vissac

In the presentation which follows, wash-ability curves, such as are commonly used in making studies preliminary to the cleaning of any coal or to the concentration of any mineral, have been reduced in each instance to a single straight line; thus all the most important characteristics of the coal or mineral are represented in a form more advantageous than that in which such data usually are shown. To obtain consistent results, float-and-sink data must be based on a single definite narrow size range, which may be designated "a coal unit." It will be shown that such units, each embodying a different size range, can be grouped to form what may be termed "a composite coal." A three-dimensional presentation will emerge, which will closely identify the coal, illustrate its characteristics in a new manner and explain many obscure facts. Float-and-sink Tests For the preliminary study of any cleaning or concentration problem, or in the control of any operation, float-and-sink tests must be made. The results of these tests are grouped in tabular form and then illustrated in various systems of curves; but if such a graphic representation is to have the utmost practical value, it must offer at least the following advantages: (I) It must be easier to read than the tabular results, and (2) it must be easy to plot, check and interpolate. The first requirement will be attained by reducing the number of curves to a minimum, and the second by some system of representation that will use only straight lines. Of the many washing curves now in use, only the "recovery curve," often known as the "composite curve"—a somewhat misleading term—will be considered; Any point on the recovery curve will show what percentage of weight of clean coal can be recovered when the mineral is washed at a certain specific gravity. As an example, the tests listed below Fig. I are illustrated in the drawing by a curve obtained by plotting (I) as abscissas the ash content of the coal recovered and (2) as ordinates the corresponding percentage of refuse discarded; but, in general practice, instead of writing down that weight, it is customary to set down its complement, which is the corresponding weight of coal recovered. From this curve can be deduced the information necessary for the solution of most practical problems. New Form of Graphic Presentation The resemblance of the recovery curve ill Fig. 1, or, for that matter, the recovery curve obtained in common practice! to a Power curve is apparent. The general equation of such a curve is Y = axn, where n is negative. Taking logarithms: log y = a + n log x. Using a logarithmic scale, the equation of the recovery curve will be Y = A + bX. On this logarithmic basis! the recovery graph will be a straight line, using the same variables as in Fig. I; namely, the ash con-

Jan 1, 1942

By Whitman E. Brown, Louis J. Erck

L. A. ROE*—This paper is one of great value to the iron ore industry. The Humphreys spiral is a relatively new tool and gives promise of being quite useful in solving certain problems of iron ore beneficiation. Spirals have been tested on a martite ore at the Benson mine of Jones and Laughlin Steel Corp. in northern New York State. Our New York ore is considerably different, physically and mineralogically, than the one mentioned in this paper, and contains only 25 pct iron. This ore can be processed on spirals to give a concentrate containing 62 pct iron with an 85 pct recovery. On our particular ore we found operating difficulties when the spiral feed was coarser than 14 mesh. These were chiefly due to excessive "build-up" of locked middlings in the spiral circuit. In extreme cases these middling particles would accumulate to such an extent that the plant had to be shut down and the spiral surge tanks cleaned out. It is interesting to note that there exists a close relationship between the results of tabling a given iron ore and concentration of this same ore on Humphreys spirals. The size range of the ore must, of course, be within those limits acceptable to spiral concentration. Comparative tests on several of our mar-tite ores showed tabling results to be the same as spiral results. The authors make no mention of the use of a tailing stream splitter (now available from the spiral manufacturer) which is a useful tool in studying iron losses in the tailings stream. 011 our particular martite ore we found a considerable accumulation of fine-sized iron ore particles in the outside portion of the tailings stream. This fraction may be amenable to further treatment. E. H. ROSE*—The authors have concluded an interesting piece of work and this paper is an excellent factual account of a rapid and somewhat unusual transi-;ion in practice in the plant described. Perhaps it was modesty on their part which caused them so casually to limit to one sentence the fact that "several other methods of concentration on the fine ores representative of the Hill Trumbull group . . . failed to produce consistently an acceptable grade and recovery of finished product." The fact is that they were confronted by a difficult mineral-dressing problem and they are to be congratulated on their courage and persistence in staying with it until a satisfactory solution was evolved. A visitor to the plant might have been mildly astonished, as I was, to see one type of concentrator handling that part of the load early in the 1947 season, its experimental replacement by another a little later, and then in 1948 to see that both types had simply disappeared and their place taken by the spirals which were operating as placidly as though they had been there all the time. In working out economic methods of beneficiating Alabama red ore, most of which development is still ahead of us, it is likely that we also will pass through a period of successive disappointments, for we too have a problem where it is next to impossible either to "guess 'end right in the first place," or, because full-scale operating cost is such an important factor, to lay the ultimate answer on the line in advance by means of laboratory experimentation. Iron ore being what it is instead of what it used to be, it is encouraging to have the example the authors have given us today that a tough nut that will not crack on the first blow or the second is apt to do so on the third or fourth.

Jan 1, 1950

US 4,152,143-Continuous precipitation of cement copper from an aqueous ore leach solution mixed with pieces of iron as the precipitant Copper depositing on the pieces of iron is loosened and removed therefrom by means of constant but regulated oscillating movement of the pieces of iron in a horizontal elongated chamber, and the loosened copper is separated and collected from the mixture E Kausel and R Nissen, assigned to Klockner-Humboldt-Deutz A G May 1, 1979 8 pp (75-100) Filed 1-12-78 (868,981) (Drawings below) [ ] US 4,156,711-Removal of metal impurities from an acidic zinc or cadmium solution prior to electrolysis. Impurities such as manganese, cobalt, nickel, and thallium are selectively precipitated by contacting the solution with persulfuric acid or an ammonium or alkali metal salt thereof while maintaining a pH value of from 1 5 to 4 5 This patent is a continuation-in-

Jan 1, 1980

By Frank Schrader

J. DANA SPERR, Jerome, Ariz. (communication to the Secretary*).¬Very little accurate information has been published about this district. Most of the geological data appearing in the technical press are based on "careful observations" made from an auto stage and a casual glance through the U. S. Geological Survey Bulletins, No. 340 of 1908 or No. 397 of 1909, both by F. C. Schrader. Mr. Schrader's report is still the best publication on the district. A really careful study of this report will uncover only a very few statements which have since proven questionable. This is a remarkable record when it is considered that only a short time was spent by Mr. Schrader in the field and that there was very little development work done at that time. The mining world and especially Mohave County, Ariz., will feel a sense of gratitude to Mr. Schrader for revising his early report. on this

Jan 3, 1917

By David M. Parkes, Junie Lindsay

A review of the movement of coal in water is undertaken from a practical rather than a theoretical view point. Installations are described in which coal is transported on gradients down to 2.5' and others which move coal at a water-coal ratio of 1:l by weight. The water cycle of the hydraulic mining system is discussed. In many applications this can be a closed circuit. The coal dewatering system is illustrated, making particular reference to the problems of storage of coal-water mixtures between the mine and the plant. Water treatment is done in thickeners down to 100 ppm which is normally sufficient for re-circulating through high pressure pumps and monitors.

Jan 1, 1978

By Chairman Hill H. H.

The Round Table Discussion on Petroleum Engineering Research was planned for two purposes. First, to review the work that has been done by petroleum engineers during the past few years on problems that have confronted the industry and, second, to suggest new studies that should be made either on the problems that have been the subject of research during the past or on problems that have arisen only recently. It was believed that by holding an informal discussion of the problems in which the petroleum engineer is vitally interested it would be possible to bring out new ideas as to the relative importance of the different problems that should be studied and to suggest new methods for attacking some of the problems that have resisted the energies of research workers throughout the industry. It was also believed that by arranging for an exchange of experiences between the different engineers it would be possible to prevent a large amount of duplication of effort in conducting research work. Those engaged in petroleum engineering research realize that there is a broad field for study and by coordinating the work it will be possible to obtain the maximum amount of information in the shortest possible time. In planning the program on Petroleum Engineering Research, nine subjects were selected for discussion and each was assigned to a man who is doing work on that subject. These men were asked to lead the discussion on the problem assigned to each one. An effort was made to choose problems of a practical nature and upon which considerable work is being conducted at the present time. Some of the men who were asked to lead the discussion were unable to attend the meeting but most of them submitted a written discussion- of the subject assigned, with the result that there was a discussion of eight of the nine problems. Professor Uren, who was asked to lead the discussion on the subject of Recent Developments in Methods for Reducing Gas-oil Ratios, was unable to attend the meeting and advised that he did not have any new ideas to contribute.

Jan 1, 1928

Prof. J. W. Richards, South Bethlehem, Pa. (in reply to several questions):—The cut representing some of the round briquettes which were under test shows that, at the brcaking-stresses, they break into lumps, and do not disintegrate into powder. The process is simplicity itself. I have followed the different processes for sintering iron-ores and flue-dust, am interested in all of them and wish them all success; but this process appealed to me strongly by its simplicity. It is in line with a method which I once tried to work out myself, but which never came to anything, namely, the agglomeration of fine iron-ores by means of Portland cement. As small an amount as 5 or 6 per cent. of Portland cement will enable fine ore to agglomerate and set into a briquette, but when I came to estimate the cost, I found it was a little too high. The Schumacher process, curiously enough, does not work well on iron-ore, but flue-dust thus treated does harden and give a strong briquette. In my attempts to find a reason for this difference, it has occurred to me that possibly the particles of flue-dust had been coated over with some sublimed silica, which might be an agent in the setting. But I found by experiment that neither sublimed silica, nor ordinary silica, nor ordinary alumina, would briquette. Chemically pure iron oxide briquetted quite hard; but the application of pressure is a necessary part of the operation. If simply moistened with the solution and allowed to stand it does not set hard, but the more pressure applied to it the hardcr it sets. Evidently the flue-dust particles must be pressed very close together in order to get the small proportion of active material wet, so that the particles shall act at their points of contact; for it is evident that only at the points of contact does the cementing action take place. The reactions are facilitated by considerable pressure, bringing the acting particles close together, and may go on with

Jan 1, 1913

By Frederic Carter

THE gold, silver, copper alloys have been the subject of several fairly complete investigations by Jänecke, Sterner-Rainer1 and others, and indeed it would seem as if almost too much labor had been expended on them when one thinks of the numerous other ternary alloys calling for more light; however, the combinations of the three metals are actually so widely used in jewelry that they merit perhaps the work done on them. There are a few properties of importance and interest not treated by the authors mentioned which the writer investigated some little time ago, and therefore he has ventured to put on record the results of some of his tests made at that time. He has chosen, as being the two series of most importance to the jeweler, only the 14 and 18-kt. golds, so the subject is by no means so inclusive as that previously treated. As stated, this paper is merely a record of tests made in a practical manner on two useful series of alloys, and is not at all a critical study of their properties. 14-KARAT ALLOYS These alloys are important because they are the most generally used in 14-kt. jewelry; by changing the proportions of silver and copper there are obtained all shades of color from the green of the alloy containing gold and silver but no copper, to the red of the alloy containing gold and copper but no silver. Many 14-kt. gold alloys are made with the addition of zinc to the three metals mentioned here; the added metal does not appreciably alter the color of the alloy nor has it, in general, much effect on the working properties; it may, however, prove useful as part of the zinc added may act as a deoxidizer and render the alloy free of gas. It is not a necessary addition because with proper precautions all the 14-kt. gold alloys containing only silver and copper in addition to the gold can be made free of gas and capable of being cold rolled without cracking. The alloys in which approximately equal quantities of silver and-copper

Jan 1, 1928

By Frederic E. Carter

THE gold, silver, copper alloys have been the subject of several fairly complete investigations by Jänecke, Sterner-Rainer1 and others, and indeed it would seem as if almost too much labor had been expended on them when one thinks of the numerous other ternary alloys calling for more light; however, the combinations of the three metals are actually so widely used in jewelry that they merit perhaps the work done on them. There are a few properties of importance and interest not treated by the authors mentioned which the writer investigated some little time ago, and therefore he has ventured to put on record the results of some of his tests made at that time. He has chosen, as being the two series of most importance to the jeweler, only the 14 and 18-kt. golds, so the subject is by no means so inclusive as that previously treated. As stated, this paper is merely a record of tests made in a practical manner on two useful series of alloys, and is not at all a critical study of their properties. 14-KARAT ALLOYS These alloys are important because they are the most generally used in 14-kt. jewelry; by changing the proportions of silver and copper there are obtained all shades of color from the green of the alloy containing gold and silver but no copper, to the red of the alloy containing gold and copper but no silver. Many 14-kt. gold alloys are made with the addition of zinc to the three metals mentioned here; the added metal does not appreciably alter the color of the alloy nor has it, in general, much effect on the working properties; it may, however, prove useful as part of the zinc added may act as a deoxidizer and render the alloy free of gas. It is not a necessary addition because with proper precautions all the 14-kt. gold alloys containing only silver and copper in addition to the gold can be made free of gas and capable of being cold rolled without cracking. The alloys in which approximately equal quantities of silver and copper

Jan 1, 1928

By Frederick Prime

THE Great or Cumberland Valley, which (under a variety of names) extends from Canada, through Vermont, Massachusetts, Connecticut, New York, Pennsylvania, Maryland, Virginia, and East Tennessee, to Alabama, is composed in part of limestones lying immediately above the Potsdam sandstone. Geologically, they belong to the era between the Potsdam and Trenton, and are commonly termed Calciferous. A peculiarity of these limestones is their great richness in limonite or brown hematite ores, which form a large part of the charges of the many blast-furnaces situated on their outcrops. The mines from which the ores are obtained are (properly speaking) only pits or quarries, from which the ore is extracted by means of picks or shovels, powder being rarely employed. The ore does not occur casually at any point in the limestone, but forms regular lines, following apparently the 'outcrops of certain beds. In Lehigh County, Penn., where I have been engaged on the Geological Survey of' the State, during the past season, there are three or four of these lines. During the progress of the survey I was much struck by the fact that the two most important and promising lines of outcrop were, one at the base of the crystalline schists (forming the South or Lehigh Mountain), and overlying the Potsdam sandstone conformably; the other, near the line of junction of the calciferous limestone with the slates of the Cincinnati epoch. The mines along these two lines, following the topography of the country, were in place, richer and more permanent than those of the belts between, which were generally leaner. A peculiarity of these two lines of outcrop, and one to which I particularly desire to draw attention, is the occurrence of what I at first mistook for a highly altered slaty limestone, but which subsequent analysis proved to consist in great part of damourite (hydrated potash mica). The following are analyses of this damourite slate I. From Fogelsville, Lehigh County, within a few hundred feet of the contact of limestone and slate, by Dr. F. A. Genth. II. From Hensingerville, Lehigh County, within 300 feet of gneiss, by Mr. Sydney Castle, of the University of Pennsylvania. III. From Allentown, Lehigh County, within 150 feet of con-

Jan 1, 1875

By Strathmore R. B. Cooke, Iwao Iwasaki, C. S. Chang

PYRRHOTITE has long been considered a gangue mineral to be eliminated as tailing in the treatment of various sulphide ores. However, in recent years the world-wide lack of sulphur resources has called attention to this mineral as a potential source of both sulphur and iron. Its importance as an economic mineral, however, has not been particularly emphasized. For this reason very little is known about its response to flotation, except that it can be depressed easily in alkaline circuit, by long aeration,1,2 addition of oxidizing agents3 or by starch.4 The object of this work was to study the floatability of pyrrhotite. This includes the effect of oxidation by aeration, of copper activation, and of change in pH.

Jan 2, 1954

By B. Ancker, E. R. Parker

The small-angle dislocation-boundary density of nickel and some of its alloys was investigated as a function of strength. It was found that the strength is a linear function of the density for pure nickel and for Ni-Ti alloys, but not for Ni-Co alloys. The results are interpreted in terms of dislocation theory. THE processes by which metals deform are still poorly understood, even though there has been a concentrated research effort in this field during the past fifteen years. Single crystals and individual grains in polycrystalline aggregates often develop a subgrain structure when deformed. Substructure formation occurs as a result of local plastic bending and its development is augmented by annealing at moderate temperatures.' Investigations made to date, largely qualitative in nature, have shown that the substructure is composed of a network of small-angle boundaries. The purpose of the present paper is to present some quantitative data on substructure (obtained by X-ray techniques) and to correlate the results with the strength of the metal in which the substructure existed. Nickel and some of its alloys were used for the experiments. The presence of certain kinds of foreign atoms greatly alters the formation and effect of the substructure. Polycrystalline tensile specimens were prepared from high purity nickel, two Ni-Ti alloys, and two Ni-Co alloys; the composition of these materials is given in Table I. Tensile specimens having a reduced section 1/4 in. diam by 3 in. long were machined from materials which were refined, cast, forged, and swaged in the authors' laboratories. The specimens were annealed for 1/2 hr at 1150°C, a treatment which produced grains having a diameter of approximately 0.5 mm. This rather large grain size was used to facilitate later examination of the substructure. Duplicate specimens of pure nickel and of each alloy were strained various controlled amounts in tension at room temperature and recovered for 1 hr at 800°C. (This strain induced prior to recovery will be referred to hereafter as the "prestrain.") One of each of the recovered specimens was pulled in tension at room temperature to obtain the stress-strain curves. The other bar was cross-sectioned in the gage length, carefully polished, and deeply etched to remove all cold-worked material. This specimen was then examined by the X-ray microscopic technique2 to determine the nature and magnitude of the substructure. The use of duplicate specimens permitted a direct correlation between tensile properties and substructure characteristics. X-ray microscopic studies were made with an apparatus constructed to have an average resolving power of about 4 microns. The monochromatic radiation reflected from grains which were oriented favorably was recorded on fine-grain photographic plates. These were examined at Xl00 which represents the true magnification, since there was essentially none in the X-ray system. This permitted detection of angular differences between subgrains of as little as 10 min. A very large number (over 100) of grains for each specimen was examined at this magnification and the number of substructure boundaries per grain was tabulated. An accurate relative measure was obtained under fixed experimental conditions, e.g., same grain size, resolving power, magnification, etc. The greatest source of error lay in counting the subboundaries, but this proved to be surprisingly small when repeated counts were made by different investigators. Furthermore, as the subsequent analysis indicates, whatever human error was introduced was not significant. Analysis of the Substructure Data When the number of substructure boundaries per grain was plotted against the frequency, skew (asymmetrical) distribution curves of the type shown in Fig. 1 were obtained. These are smoothed curves for the 1 atomic pct Ti in nickel alloy subjected to various prestrains and are representative of the curves obtained with all the metals. Since skew-distribution curves cannot be analyzed by elementary statistical methods, detailed investigations were undertaken in order to 1—test the consistency

Jan 1, 1955