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By Henry J. Sandri

ACQUISITION JUSTIFICATION There are many reasons why companies consider acquisitions as a means to expand their operations. Some wish to reduce the impact of business cycles on their businesses. Others seek firms within the same industry for expansion and increased market share. Still others diversify in order to avoid takeovers. Whatever the reasons or justification, an evaluation of an acquisition candidate should be systematic and thorough. To many financial managers the concept of a systematic acquisition evaluation indicates the need for a regular set of evaluation criteria. While these are available from numerous sources, one basic parameter frequently overlooked is the application of these criteria to an industry which is different from the acquirer. This becomes particularly important when evaluating firms within the mineral industry. The mineral industry is significantly different from other industries to require different valuing techniques. • This paper will present a number of reasons why an acquisition candidate in the mineral industry should be evaluated differently from other acquisitions, including by other mineral firms. Additionally, this paper will review the most appropriate means of valuing a mineral firm. • Firms considering the acquisition of a mineral firm should understand the nature of the industry before ever making a tender offer. Some of the general considerations include the following: • Level of Capital Intensity: In the mid-1980's the start up cost for a gold mine has been between 20-200 million dollars and 500-1,500 million dollars for a bauxite operation. • Global Nature of Competition: Except for certain industrial minerals, most minerals and metals are traded worldwide and many on national exchanges, such as COMEX. • Start-Up Time: Many mining operations in developed and developing countries have long lead times, 7 to 10 years in some cases, prior to the start-up of production. • Long Term Nature of Investment: For most mineral operations payback usually occurs at least 7 years after production has started. Additionally, many mining operations will continue producing for 80-100 years. • High Level of Risk: The number of factors that a mining firm cannot control such as grade, volume, world supply and demand, plus the long payback periods tend to classify mineral firms at a higher than average risk compared to other investments. • Cyclical Nature: The mineral industry is cyclical in nature, experiencing long troughs and explosive peaks, thus making timing a critical issue. • Labor Intensive: Even with the large capital requirements needed to operate a mine, most mines are labor intensive in proportion to their capital equipment. • Location: Obviously, the nature of this industry requires operators to work in difficult locations, frequently far from civilized localities, in poor weather conditions and without proper supply and distribution infrastructure. One of the most important considerations is an understanding of asset replacement and asset value. Unlike manufacturing concerns, firms in the mineral industry are working toward the elimination, through depletion, of their asset base. Product flexibility is not available to a mining operation. A mineral firm basically has two options as its resource base is depleted: 1) replace the asset with new production, or 2) deplete the asset and close down operation, as in the South African gold mining model referred to later in this paper. An understanding of the

Jan 1, 1985

By James W. Halley

' FINE-GRAINED " steels have been standard products for many years. This paper describes an investigation of the effects of some of the more common grain-growth; inhibitors used to produce these steels. The properties, response to heat-treatment, and the deoxidation practice necessary to produce "fine-grained" steels have been the subjects of numerous papers. It has been shown that a substantial quantity of' aluminum is necessary to produce this type of steel, and it has been indicated that titanium and zirconium produce a similar result. For some time there was a lively argument between those who felt that aluminum refined the grain and those who felt that aluminum oxide was the effective agent. This argument subsided with an apparent victory for those promoting aluminum oxide. Most of the work on grain size has divided steels into two broad classifications based upon McQuaid and Ehn's original carburizing test at 1700°F. or some similar test at this temperature. If the steel coarsened at this temperature, it was coarse grained, while if it did not it was fine grained. Quantitative data concerning how much a certain amount of aluminum raised the coarsening temperature and affected the properties, all other factors being constant, are very meager. Similar information regarding titanium and zirconium is practically nonexistent. The published information on aluminum yields some quantitative information. Epstein, Nead and Washburn' gave the first quantitative information on the amount of aluminum necessary to prevent grain growth at 1700°F. They showed that the addition of a pound to a pound and a half of aluminum per ton (0.05 to 0.075 per cent) would assure steel that would not .coarsen during a McQuaid-Ehn test at 1700°F. Herty, McBride and Hough2 reported that a steel containing 0.020 per cent acid-soluble aluminum coarsened between 1742° and 1832°F., while steels containing 0.016 per cent and 0.017 per cent acid-soluble aluminum coarsened between 1652~ and 1742°F. compared with similar aluminum-free steels that started to coarsen at 1580°F. Herty3 also showed a marked improvement in low-temperature notched impact resistance with increasing acid-soluble aluminum up to 0.030 per cent. McQuaid4 compared the coarsening of steels containing 0.011 to 0.204 per cent total aluminum and found a maximum coarsening temperature at 0.098 per cent aluminum. He had no samples between 0.015 and 0.098 per cent aluminum. Houdrement5 found a marked decrease in coarsening temperature with aluminum contents above 0.50 per cent. Kinzel, Crafts and Egan6 found that aluminum and zirconium improved thy low-temperature impact resistance of a low-alloy steel, while titanium was detrimental. Sims7 shows that sulphur increases the coarsening temperature and that the maximum coarsening temperature is between 0.04and 0.06 Per cent added aluminum. The

Jan 1, 1946

By Anthony William Deller

MAJOR battles in the present war have been fought in American research laboratories. Without the outstanding contributions made by our scientists, engineers, and technologists in mining and metallurgy, many of our achievements in the present war would have been impossible. All recognize the fact that modern research has found the answer to problems which seemed insuperable. For the duration, many of these inventions must be maintained as war secrets. But aside from these, the record of accomplishment in peace and war, especially in the past few decades, known to all, demonstrates what scientific and industrial research can accomplish. It may be regarded as axiomatic that the development of modern industry is based principally upon research devoted to making inventions and discoveries. We have come a long way from the sixteenth century, when Agricola published his classical "De Re Metallica:" With our vastly increased knowledge we are now commercially producing dozens of metals entirely unknown at that time. Further, with our modern methods of research and development, a large number of invaluable alloy compositions have been produced. These include numerous age-hardenable alloys, cupronickels, "Everbrite", "Everdur", "Duralumin", "Elinvar", "Hastelloy", "Inconel", "Invar", "Monel", "Ni-chrome", "Ni-Hard", "Ni-Resist", "Permaloy", "Silcrome", stainless steels and irons and other alloy steels, "Stellite", and zinc die-casting alloys.

Jan 1, 1945

NEW MEMBERS The following list comprises the names of those persons who became members during the period of May 10, 1917, to June 10, 1917. ANDERSON, JAMES P.,-Mgr. of the Mines of the Ringwood Co., 50 Church St:, New York, N. Y. BAKER; THOMAS C., Mine Supt., Cia. Santa Gertrudis, S. A. Pachuca, Hidalgo, Mexico. - BARCUS, W. J.. E., Min. Engr., Mining and Metallurgical Dept., General Chemical Co., 25 Broad St., New York,. N. Y. . BENNETT, GEORGE N.,.Min. Engr., Butte & Superior Mining Co., 616 West Gold St., Butte, Mont. BROCKMANN, GUILLERMO, Banker, Gmo. Brockmann & Co., Room 3115, 120 Broadway, New York, N. Y. BROWN, CLYDE L Mining, Box 703, Goldfield, Nev. BRUNSKOG, CARL W., Draftsman, Consolidated Arizona Smelting Co., Humboldt, Ariz. BURRELL,. OSSIAN C Mgr., American Zinc Co. of Tenn., Mascot, Tenn.

Jan 7, 1917

By John T. Crawford

Much has been written of late regarding the flotation of coal as a means of reclaiming the valuable portion of the fines encountered in nearly all methods of coal preparation. Whether the process be wet or dry, whether the dust be sent through the entire process or removed prior to the cleaning by some such method as screening or aspiration, one of the final products consists of a considerable proportion of — 48-mesh material. The percentage of this —48-mesh material depends upon the mining method, transportation, storage, and method of preparation. The tonnage of this dust material ranges from 1 to 10 per cent of the total output of the cleaning plants. Four methods of disposal are available for this coal: 1. Disposal with the refuse from the plant. 2. Addition, after being reclaimed from the wash water, or dust collectors, without cleaning to the larger sizes. 3. Separate disposal as a pulverized fuel. 4. Cleaning so that addition to the larger sizes benefits the product as a whole. It is also true that flotation in one form or another is the only known way to effectively clean this material. While some processes do a reasonable cleaning job down to and including +l00 mesh, by far the greater majority stop at or short of the + 48-mesh size. Much of the literature on coal flotation passes by the fred pulp density and size by merely stating that the feed varies from 20 to 30 per cent solids and that the size range is from — 1/4 in. or — 1/8 in. to 0. Small wonder then that some operators with entirely different conditions, and not knowing the machine capacity, throw up their hands in despair when flotation is mentioned. Too much parallel is drawn between flotation methods as applied to ores and as applied to coal, to the detriment of the latter. In the flotation of metalliferous ores the feed pulp density ranges from 20 to 30 per cent solids, depending upon the amount of mineral to be floated and upon the size analysis. Thus where 2 to 5 per cent of the

Jan 1, 1936

By John T. Crawford

Much has been written of late regarding the flotation of coal as a means of reclaiming the valuable portion of the fines encountered in nearly all methods of coal preparation. Whether the process be wet or dry, whether the dust be sent through the entire process or removed prior to the cleaning by some such method as screening or aspiration, one of the final products consists of a considerable proportion of — 48-mesh material. The percentage of this —48-mesh material depends upon the mining method, transportation, storage, and method of preparation. The tonnage of this dust material ranges from 1 to 10 per cent of the total output of the cleaning plants. Four methods of disposal are available for this coal: 1. Disposal with the refuse from the plant. 2. Addition, after being reclaimed from the wash water, or dust collectors, without cleaning to the larger sizes. 3. Separate disposal as a pulverized fuel. 4. Cleaning so that addition to the larger sizes benefits the product as a whole. It is also true that flotation in one form or another is the only known way to effectively clean this material. While some processes do a reasonable cleaning job down to and including +l00 mesh, by far the greater majority stop at or short of the + 48-mesh size. Much of the literature on coal flotation passes by the fred pulp density and size by merely stating that the feed varies from 20 to 30 per cent solids and that the size range is from — 1/4 in. or — 1/8 in. to 0. Small wonder then that some operators with entirely different conditions, and not knowing the machine capacity, throw up their hands in despair when flotation is mentioned. Too much parallel is drawn between flotation methods as applied to ores and as applied to coal, to the detriment of the latter. In the flotation of metalliferous ores the feed pulp density ranges from 20 to 30 per cent solids, depending upon the amount of mineral to be floated and upon the size analysis. Thus where 2 to 5 per cent of the

Jan 1, 1936

By D. M. Boulin, E. S. Greiner

Single crystals of vanadium were bent at 293" and 77°K to a maximum fiber strain of about 1 pct. Analysis of slip line and etch markings of- crystals deformed at either temperature show the slip planes are {112}. The slip directions at 298° and 77°K, deterwined from the asterism axes of rotation of crystals compressed in a {110} direclion, were (111). Etch pits, associated with dislocations, were observed in the plastically deformed vanadium. There was no evidence of mechanical twinning. THIS paper presents results on single crystals of vanadium plastically deformed by bending and compressing at 298° and 77°K. Bcc metals have been observed to slip on {110}, (1121, and (123) planes while the slip direction has invariably been found to be ( 111) 1 Lindley and smallman2 have studied the deformation intension of polycrystalline vanadium between 298° and 20°K and reported that at and above 77°K the deformation is predominantly by slip, but at 20°K the deformation is associated with twinning. Later, Edington and smallman3 found that single crystals of vanadium compressed in a (111) direction at 77°K deformed by twinning on { 112}( 111) systems. Clough and pavlovic4 have reported that mechanical twins were observed in vanadium loaded by impact at 77°, 173°, and 195°K, respectively. PREPARATION OF SINGLE CRYSTALS The vanadium single crystals were made from commercial vanadium reported to contain 0.03 pct C, 0.03 pct 0, 0.02 pct N, 0.0X* pct Ca, 0.0X pct Si, proximately 0.8 cm diam, 4 cm long and were grown in (100) and (110) directions. A crystal for studies of etch pits was gound to have a face parallel to a {l00} plane by the Bond crystal-orienting technique.7 In order to avoid straining, the crystals were placed on the steel mount with a low-melting organic compound (glycol phthalate) before grinding. Crystals for the bending experiments were ground to have the four side faces parallel to ( 100) planes. The crystals were electropolished8 in 10 pct H2So4 using a current density of about 3 amp per sq cm to remove the strained surface material. The crystals were bent slowly by three-point loading in a stainless-steel jig designed by Sylwestrowicz.9 The end rollers of the jig were 3.8 cm apart. DEFORMATION AT 298°K The bent vanadium crystal, after removal from the jig, had a radius of curvature of 20.4 cm over the 2-cm length close to the center loading roller, where the maximum bending moment occurred. This radius of curvature corresponded to a maximum fiber strain of 0.9 pet. The side faces contained slip bands as shown in Fig. 1. These bands are straight where the strain is high, top and bottom of micrograph, but are curved on either side of the neutral axis in the center. This curvature of the slip bands in the low-stress area may be due to cross slip. The plastically deformed crystal was subsequently electropolished and then electroetched in 10 pct H2SO4 solution, using a current density of 0.25 amp per sq cm. The structure is shown in Fig. 2. The directions of the traces on two adjoining faces were plotted stereo graphically, Fig. 3.* Since there were two sets of

Jan 1, 1968

By K. R. Y. Simha

Successful explosive gas well stimulation requires a thorough understanding of explosively driven cracks under confining in-situ stresses. In a previous paper (Simha, et a1 1983) the problem of explosively driven cracks was experimentally investigated to reveal the features of crack propagation. It was observed that the explosively driven crack propagation is the result of two different but overlapping phases. The first phase involving the initiation and early time crack propagation is entirely governed by the explosively generated stress transients. The rapidly decaying stress transients then lead to the second phase of crack propagation largely controlled by the in-situ stresses. The purpose of this paper is to more fully understand the characteristics of the first phase concerning the initiation and early time propagation of explosively driven cracks. Experiments are conducted with plastic models under biaxial compression and the dynamic event is observed with a high speed multiple spark gap camera of the Cranz-Schardin type. The experimental observations are utilized to propose analytical models of crack initiation under explosive loading to aid in the design of multiple fracturing necessary for successful application of modern well stimulation techniques.

Jan 1, 1984

By Pradeep K. Rohatgi, Clyde M. Adams

Structures produced upon solidification of the eu-tectic composition (33 wt pct Cu) aluminum copper alloy have been examined as a function of freezing rate dfs /d? , the rate of change of fraction solid (fs) with time (8). Slow (dfs/d? = 0.0016 sec-1), intermediate (dfs/d? = 0.02 sec-1) and rapid (dfs/d? = 0.4 to 7.30 sec-1) freezing rates were used. The lamellar Al-Cual2 eutectic is arranged in the form of rod-shaped colonies at rapid freezing rates. The colonies are aligned parallel to the direction of heat flow, whereas the lamellae within the colonies are aligned at various angles, as high as 90 deg, to the direction of heat flow. The colony spacing (C) is proportional to the square root of inverse freezihg rate. The relationship is C = 15.5(dfs/d?)-1/2 where C is in µ and 8 is in sec. The ratio of colony spacing to lamellar spacing is greater than 20.0 and increases with a decrease in the freezing rate. A duplex dendritic structure is produced at intermediate freezing rates. A fine lamellar eutectic is arranged within the dendrites (exhibiting side branches at an angle close to 60 deg from the main stem) and a coarse irregular eutectic appears in the interdendritic regions. The duplex eutectic structure is also produced at slow freezing rates. However, at slow freezing rates there is a Platelat of CuAl2, along the center of the main stem of each dendrite and the other lamellae are arranged perpendicular to the central platelet. THE eutectic between CuA12 and a! aluminum has been reported to freeze in a lamellar form by several workers.'-3 chadwick4 has measured the interlamel-lar spacing as a function of growth rate. Kraft and Albright2 have reported on irregularities in the lamellar structures, and have proposed growth models which account for the formation of faults during solidification. In certain instances the lamellar eutectic has been found to exist in colonies. The colony formation315 has been attributed to the breakdown of a planar liquid-solid interface due to rejection of impurities. The aim of the present work is to study the structures produced from the eutectic aluminum-copper alloy under relatively fast solidification rates, such as encountered in casting and welding operations. The solid-liquid interface presumably remains planar under conditions of slow unidirectional freezing which produce lamellae aligned parallel to the direction of heat flow. The local growth velocities are the same over the entire interface and are equal to the rate of growth of the all-solid region. The spacing between the eutectic lamellae is inversely proportional to the square root of the growth rate of the all-solid region. Under the freezing conditions used in the present study, the solid-liquid interface is cellular or dendritic and the local growth velocities are different in the different regions of the interface. The relationship between the growth rate of the all solid region and the local growth velocities varies with the location and the shape of the interface. The growth rate of the all-solid region is, therefore, an inadequate parameter to describe the eutectic micro-structures which depend upon the local growth velocities. For this reason the structures have been examined as a function of freezing rate, dfs/d?, where fs is the fraction solidified at time 0. The freezing rate was varied by a factor of 4000. The relationship between the freezing rate, dfs/d?, and the growth velocit of the all solid region depends upon the specimen geometry and the shape of the interface. EXPERIMENTAL PROCEDURES The A1-33 pct Cu alloy used throughout this study was made in an induction furnace, using electrolytic copper and aluminum of commercial purity (99.7 pct), the primary impurities being silicon (0.12 pct), iron (0.14 pct), and zinc (0.02 pct). Three ranges of freezing rates were investigated: 1) A spectrum of rapid freezing rates (ranging from 0.40 to 7.30 sec-1) was obtained in arc deposits made on 2-in. thick cast plates of the eutectic alloy. The arc was operated at constant power and was made to travel at constant velocity on the surface of the plate that was in contact with the chill surface during solidification. The pool of liquid metal formed under the moving tungsten arc solidified rapidly by heat extraction through the unmelted plate. Conditions of unidirectional heat flow were achieved near the fusion zone interface, especially in the center of the arc deposits. The great advantage of the arc technique is that rapid cooling and freezing rates can be varied in a qualitative way. The correlation between the arc parameters and the solidification rate is given by the following relationship:6-8

Jan 1, 1970

EDWARD W. PARKER,* Philadelphia, Pa. (written discussion ?).-The two papers on coal-mine costs and pride fixing that Mr. Norris has contributed to the Transactions possess as much general interest and are of as much value to the coal-mining industry as any papers that have been presented in recent years. Until recently one of the troubles with the coal business, and especially the bituminous branch of it, has been that because of the lack of a uniform system of cost accounting (many operators, I regret to say, not having had any system at all), the industry as a whole may be said not to have known where it was at. The system adopted by the Federal Trade Commission may not be absolutely perfect but it has accomplished something in that it has compelled a uniform method of reporting and tabulating costs giving results of these compilations which are comparable. The Institute and the coal-mining industry owe a vote of thanks to, and of confidence in, Mr. Norris and his two associates on the Engineers Committee of the Fuel Administration, Messrs. Garnsey and Allport, for the great work they have done in interpreting the results compiled by the Federal Trade Commission, not to speak of the personal sacrifices made by them in giving their services to the government. Those who have read Mr. Norris' paper will probably join me in wishing he had brought out a little more fully the real meaning of the charts so far as they indicate the difference between the cost of producing a ton of anthracite and the price the operators receive for their product. Mr. Norris could have done this more satisfactorily than anyone else. It seems to me that particular attention should be drawn to the fact that, according to these charts, and the tables accompanying them, not less than 25 per cent. of the total output of anthracite, whether "company" or "individual," during the period covered by Mr. Norris' paper,

Jan 4, 1919

By J. P. Dovel

Having been requested to prepare a paper referring especially to my patents as applied to blast furnaces, I shall confine my discussion to those improvements and inventions pertaining directly to the blast furnace itself, omitting a number of patents pertaining to blast furnace operations. I spent the early part of my life in the construction of blast furnaces, from rivet-heating to drafting and designing, much of the work relating to repairs and rebuilding. Later, as I became more interested in maintenance and operation of a group of blast furnaces, one fact especially made a lasting impression on me; namely, that a very expensive piece of equipment was very short lived, and the expense of replacement, relining, etc., in many instances consumed most of the profits made while in actual operation. As far back as 1910, I began to lay plans to build with a view to permanency and not merely for a blast, the common expression at that time, which really meant only one or two years in southern practice. Since we did not then blow so hard most failures occurred in the bosh and hearth. The failure of either generally meant a complete new lining, as the inwall did not look good enough to last another blast. At that time we were using two types of hearth, one of heavy steel plate protected by well and sprays on the outside, and one of heavy cast iron, made in sections and bound together with wrought-iron bands. The former type proved dangerous, for if the iron should come through, as it frequently did, it would cut away the steel plate, quickly turning large quantities of molten iron into the water, causing a severe explosion and costly repairs. The cast-iron type gave trouble also by the iron finding its way through the joints between the sections, which was not so serious, since the iron would not cut a way the heavy cast-iron sections very quickly, and generally caused only small damage, and repairs were easily made. Both types have been improved; the former by the introduction of cast-iron water-cooled plates, placed on the inside of the steel jacket. This has proved to be very good construction, but has no real claim to permanency. As the cast-iron plates cannot be replaced from the outside, the operator must assume that some time, at no late date, he must replace them from the inside, which will mean a blowing out of the furnace. The heavy cast-iron hearth has been improved by making the

By G. C. Broadhead

THE lead district of Southeast Missouri covers an area of over 3000 square miles, including Maries County on the west, Jefferson on the east, Franklin on the north, and part of Madison on the south, or parts of ten counties. A general section of the rocks of the southeast part of this region would be about as follows, numbering from the top 1. Sandstone (the second of Missouri geologists), - 20 feet. 2. Cbert beds-beds of passage below, - 125 feet 3. Magnesian limestone, chert, and quartzite, - 100 to 300 feet 4. Lower magnesian limestone, - 100 to 150 feet 5. Gritstone and lingula beds, - 50 feet 6. Ozark marble beds, - 5 to 20 feet 7. Sandstone and conglomerate, - 5 to 90 feet 8. Porphyry, Archaean. 9. Granite, The thickness is approximate, for it is not possible to obtain the correct thickness of the various beds. No. 1 may be seen as de¬tached outliers or loose masses of a hard sandstone or quartzite, and is found on the hilltops in the southern part of Madison County, in like topographical position in Reynolds County and the western part of Washington County. No. 2 consists of alternations of chert, clay, and quartzite. It is the formation which contains most of the limonite deposits of Central and Southern Missouri. In Reynolds County shafts have pene¬trated it 75 feet. Outcrops there and in Madison would indicate it to be at least 125 feet thick. Fossils obtained in various places prove it clearly to be of the age of the calciferous sandrock of the New York system, and Nos. 1 and 2 may also be referred to the age of the second sandstone of Missouri. No. 3 consists chiefly of thick beds of ash, drab and flesh-colored magnesian limestone, both coarse and fine-grained. These beds, where they occur, in Washington, Jefferson, and the southern part of Madison Counties, contain a good deal of quartz in drusy cavities. In Washington County the limestones are beautifully ramified by a system of connected drusy cavities generally lined with minute quartz crystals arranged in botryoidal and mammillary forms, and called u mineral blossom " by the miners. This is the lead-bearing rock of Washington County, but in the southern part of Madison it does not appear to be galeniferous. It is also undoubtedly the equivalent of

Jan 1, 1877

By G. C. Broadhead

The lead district of Southeast Missouri covers an area of over 3000 square miles, including Maries County on the west, Jefferson on the east, Franklin on the north, and part of Madison on the south, or parts of ten counties. A general section of the rocks of the southeast part of this region would be about as follows, numbering from the top: 1. Sandstone (the second of Missouri geologists),.... 20 feet. 2. Chert beds—beds of passage below,...... 126 " 3. Magnesian limestone, chert, and quartzite,. .. 100 to 300 " 4. Lower magnesian limestone,......100 to 150 " 5. Gritstone and lingula beds,....... 50 " 6. Ozark marble beds,........5 to 20 " 7. Sandstone and conglomerate,. .. .. 5 to 90 " 8. Porphyry, Archæan 9. Granite, The thickness is approximate, for it is not possible to obtain the correct thickness of the various beds. No. 1 may be seen as detached outliers or loose masses of a hard sandstone or quartzite, and is found on the hilltops in the southern part of Madison County, in like topographical position in Reynolds County and the western part of Washington County. No. 2 consists of alternations of chert, clay, and quartzite. It is the formation which contains most of the limonite deposits of Central and Southern Missouri. In Reynolds County shafts have penetrated it 75 feet. Outcrops there and in Madison would indicate it to be at least 125 feet thick. Fossils obtained in various places prove it clearly to be of the age of the calciferous saudrock of the New York system, and Nos. 1 and 2 may also be referred to the age of the second sandstone of Missouri. No. 3 consists chiefly of thick beds of ash, drab and flesh-colored magnesian limestone, both coarse and fine-grained. These beds, where they occur, in Washington, Jefferson, and the southern part of Madison Counties, contain a good deal of quartz in drusy cavities. In Washington County the limestones are beautifully ramified by a system of connected drusy cavities generally lined with minute quartz crystals arranged in botryoidal and mammillary forms, and called " mineral blossom " by the miners. This is the lead-bearing rock of Washington County, but in the southern part of Madison it does not appear to be galeniferous. It is also undoubtedly the equivalent of

By David H. Carlson, John H. Johnson

The paper presents background information, a description of mine characteristics that affect air monitoring techniques, and a review of Portable measurement techniques and instruments for gas and particulate matter sampling. A general review of the laboratory and field research being conducted at Michigan Technological University in the area of diesel emissions is presented. The facilities involved with this research are also described. These are the experimental mine, the diesel dilution tunnel test cell, the mine air monitoring lab (MAML), portable instruments, and the production mines used.

Jan 1, 1982

By B. L. Averbach, Morris Cohen, L. L. Seigle

Free energies, enthalpies, and entropies of mixing of Ni-Au solid solutions containing 5 to 95 atomic pct Ni have been determined by the electromotive force method at 700° to 900°C. The thermodynamic activities exhibit large positive deviations from Raoult's law, and the entropies of mixing are almost twice those of ideal solutions. The enthalpies of mixing are positive (heat is absorbed) and are attributable to the lattice distortional energy resulting from the size difference between the nickel and gold atoms. This factor appears to be responsible for the miscibility gap at lower temperatures. IN the thermodynamic study of metallic solid solutions, most interest has been directed toward systems with negative deviation from Raoult's law, namely, those exhibiting superlattice or compound formation. The results of previous investigations are summarized in recent publications.'-' Relatively little experimental work has been carried out on solid solutions which manifest a positive deviation, possibly because the range of solubility in such cases is usually quite limited. Nevertheless, the relationship of the thermodynamic properties of these solutions to diffusion, nucleation, and precipitation in the solid state are of considerable importance. The binary Ni-Au alloys are particularly suited to an investigation of these relationships. Despite the presence of a miscibility gap at lower temperatures, Fig. 1, indicating a large positive deviation from Raoult's law, complete solid solubility is found above 840°C. Moreover, the difference in the atomic scattering powers of nickel and gold is sufficiently great to permit X-ray diffraction studies of atomic arrangements and pre-precipitation phenomena. Radioisotopes of both nickel and gold are available for diffusion work, and finally, a large difference in nobility between the two elements facilitates measurement of the thermodynamic properties. The present paper describes the experimental determination of the free energies, enthalpies, and entropies of mixing of solid Ni-Au alloys. Table I gives a list of the symbols used in the paper. Experimental Method The stability of nickel chloride relative to gold chloride" indicated that the galvanic cell method could be used for determining the thermodynamic properties of Ni-Au alloys. An electrolytic cell (Fig. 2) was constructed, similar to that of Weibke and Matthes,7 in which the electrodes were solid nickel and Ni-Au alloys, and the electrolyte was a fused mixture of alkali chlorides containing NiCl,. The cell electrodes were made from fine gold granules and carbonyl nickel shot melted together under argon, chill cast, swaged to 1/16 in. diam rod, and annealed for one week at 850°C. Commercial reagent and chemically pure grade salts, purified by dehydration, were used for the electrolyte. The cell, operating in an atmosphere of purified argon, was heated in a resistance-wound cylindrical furnace whose temperature was controlled to within ±0.5ºC. The potential developed between the pure nickel and the alloy electrodes, which is related to the thermodynamic properties of the alloys by standard equations to be presented later, was measured with a potentiometer and a mirror galvanometer sensitive to 10-7 v. Dehydration of the electrolyte was carried out in the assembled cell by evacuating at 100°C for about

Jan 1, 1953

By H. Conrad, V. Damiano, J. Hanafee, N. Inoue

The effects of hydrostatic pressure up to 400 ksi at 25" to 300°C on the mechanical properties of three forms of commercial beryllium (hot-pressed block, extruded rod and cross-rolled sheet) were investigated. Three effects of pressure were studied: mechanical beharior under pressure, the effect of pressure-cycling, and the effect of tensile prestraining under hydrostatic pressure on the subsequent tensile properties at atmospheric pressure. For all three materials the ductility increased with pressure whereas the flow stress did not appear to be significantly influenced by pressure. An increase in the subsequent atmospheric pressure yield strength generally occurred as a result of pressure-cycling or prestraining under pressure, whereas either no change or a decrease in ductility occurred. The only exception to this was sheet material, which exhibited some improvement in ductility following a pressure-cycle treatment of 304 ksi pressure. The effects of pressure-cycling and prestraining were relatively independent of the temperature at which they were conducted. Stabilized cracks of the (0001) type were found in hot-pressed specimens and {1120) type in extruded and sheet specimens following straining under pressure. Also, pyramidal slip with a vector out of the basal plane, presumably c + a, was identified by electron transmission microscopy for extruded rod and for sheet strained under pressure. Small loops similar to those previously reported were found after straining at pressures of the order of 300 ksi. THE use of beryllium in structures is limited because of its poor ductility under certain conditions. Therefore, one objective of the present research was to determine if the ductility of beryllium at atmospheric pressure could be improved by prior pressure-cycling or prestraining under hydrostatic pressure. Another objective was to study the mechanisms associated with the plastic flow and fracture of the polycrystalline form of this metal with pressure as an additional variable. Since the early work of Bridgman,1 it has been recognized that many materials which are brittle at atmospheric pressure exhibit appreciable ductility when strained under high hydrostatic pressure. This effect has been reported for beryllium by Stack and Bob-rowsky2 and by Carpentier et al.3 and has been attributed to the operation of pyramidal slip systems with slip vectors inclined to the basal plane while cleavage or fracture is suppressed.4 That such slip may occur simply by the application of pressure alone without external straining (pressure-cycling) is suggested by the results on polycrystalline zinc5 and polycrystalline beryllium,6 where nonbasal dislocations with a vector (1123) were reported. A significant improvement in the ductility of the bee metal chromium by pressure-cycling has been reported.7 On the other hand, limited studies on the pressure-cycling of the hcp metals zinc67819 and beryllium6 indicated no improvement in ductility; there only occurred an increase in the yield and ultimate strengths. The study on beryllium was limited to hot-pressed material. Consequently, additional studies on the effects of pressure-cycling on other forms of beryllium seemed desirable, especially since for chromium some authors10 have been unable to detect any improvement in ductility while others find a large improvement.7 That the ductility of polycrystalline beryllium at atmospheric pressure might be improved by prior straining under hydrostatic pressure was suggested by the known beneficial effects of cold work on the ductile-to-brittle transition temperature in the bee metals. It was reasoned that, by straining under hydrostatic pressure, fracture would be suppressed, and during the propagation of slip from one grain to its neighbor dislocations with a vector inclined to the basal plane"-'4 would operate. Upon subsequent straining at atmospheric pressure, these dislocations with a nonbasal vector would continue to operate and thereby reduce the tendency for fracture to occur, by assisting in the propagation of slip across grain boundaries and by interacting with any cracks that may develop. It was recognized that maximum improvement in ductility would probably occur at some optimum amount of prestrain under hydrostatic pressure. If the pre-strain was too small, an insufficient number of dislocations with a nonbasal vector would be activated; if it was too large, internal stresses (work hardening) might increase the flow stress more than the fracture stress, or incipient cracks or other damage could develop. EXPERIMENTAL PROCEDURE 1) Materials and Specimen Preparation. The materials employed in this investigation consisted of hot-pressed block (General Astrometals, CR grade), extruded rod (General Astrometals, GB-2 grade with a reduction ratio of 8:1), and cross-rolled sheet (Brush S200, 0.065 in. thick). The analyses of these materials and mechanical properties at room temperature and atmospheric pressure are given in Table I. The grain size of the hot-pressed block was 15 to 16 µ, that of the extruded rod 10 to 11 µ, and that of the sheet 7 to 10 µ in the rolling plane and 5 to 6 µ in the thickness, all determined by the linear intercept method. Al-

Jan 1, 1969

By J. D. Lubahn

The Bauschinger effect, or rounding of the corner of the stress-strain curve upon reloading, represents a temporary apparent softness that is more pronounced at large strains than small and for complete unloading than for partial unloading. Interrupted creep tests on copper exhibit a similar temporary softness (high creep rate) upon reloading. The fact that the strainwise dying-out time of these effects is the same in both tensile and creep tests shows that they are related. Thus, the term Bauschinger effect appears to embrace behavior following partial or complete unloading and reloading in addition to behavior following reversed loading. It is suggested that the term may properly apply also to certain creep behaviors following a small load decrement. INTERRUPTED tensile tests at low temperatures show1 a rounding of the corner of the stress-strain curve for reloading, which indicates a temporarily low deformation resistance. In the absence of recovery, the curve soon rises to the value that would have prevailed if the test had not been interrupted. The rounding of the reloading tensile curve has sometimes been referred to1 as the Bauschinger effect, although the term is more commonly applied to low deformation resistance in compression following tensile prestrain. The unusually broad usage of the term Bauschinger eflect in ref. 1 seems justified by the obvious interconnection of the various behaviors to which it has been applied.' In fact, the following discussion will indicate that still broader usage might be desirable. The Bauschinger effect is common at room temperature but apparently disappears at higher temperatures.2 Interrupted creep tests and tensile tests were made on certified OFHC copper (nongaseous impurities exclusive of silver were 0.004 pct), cold drawn 84 pct to ½ in. diam, and annealed at 600" (about 0.025 mm grains) or 850°C (about 0.2 mm grains). The tests were made in standard creep or tensile machines, using an O.S. Peters microformer-type extensometer or, for the small plastic strains, a special arrangement employing General Electric magnetic gage heads.' Interrupted creep tests at room temperature show3,4 an initial softness after reloading, manifested by an initial creep rate that is higher than that which would have prevailed if the test had not been interrupted. Fig. 1 shows some typical examples. This effect is apparently temporary (as is that in tensile tests): in four of the five tests shown, the log rate vs strain curve becomes parallel to an

Jan 1, 1956

By Robert W. Hunt

(Cleveland meeting, October, 1912.) PERHAPS of all the scientific economic questions which have been claiming the attention of capitalists, metallurgists, manu-facturers, directors of public utilities, and the general public of America, during the last few years, none have been of more importance than the one relating to the wear and safety of steel rails. The discovery of the Bessemer process made possible modern railway development. In that growth, as has generally happened in all progressive movements, ill its department have not remained equally balanced. Iron rails permitted the construction of roadways for the passage of power-driven vehicles. In time the speed and weight of such carriages proved too much for the wearing-qualities of the rails, and the limit of railway capacity seemed to have been reached. Bessemer made his invention, which was soon perfected and developed, especially as related to steel rails, and thereby increased the limit of capacity, acid vastly greater railway progress was, made possible. The Siemens-Martin open-hearth process followed, and was later supplemented by the Thomas-Gilchrist basic improvement. For a time the Bessemer steel rails of commerce Were, more than equal to all that was asked of them, but this did not long continue, as evidenced by the records in our Transactions. Revolutionary changes occurred in the industrial world, and in no part of it more than in steel-rail manufacture. Great and powerful commercial combinations were made, whose financial resources made possible the supplanting of the then most efficient blast-furnaces, steel-works, mid mills, by others of theretofore unimagined capacity. Old traditions and practices of steel-making were wiped away, and, in too many cases, output was apparently the chief aim, with the result that much dissatisfaction with the wear and safety of rails was felt by railway officials, and the general public was concerned as to its safety when traveling. The climatic conditions of the winter

Dec 1, 1912

By D. Weinstein

Yieldilzg in annealed arc-cast molybdenunz in torsion was studied as a function of strain rate and tem-perature. The temperature dependence of the yield point for different strain rates was used to calculate a heat of activation for the yield point. The heat of activation was not a constant but was approximately a linear function of the stress at yield. It is proposed that the rate effect in yielding is determined in part by a site place-change of C (or other interstitial atom) in the metal. THE low-temperature embrittlement phenomenon in metals and alloys has been known to exist for a long time. Although a transition from ductile to brit-tle behavior has been observed in some close-packed hexagonal metals1 and a face-centered cubic alloy, the most common class of metals exhibiting this be-havior has a body-centered cubic lattice structure. For example, a ductile to brittle transition has been observed in iron,3 molybdenum,4 chromium,5 colum-bium,6 and tungsten.7 In the present investigation, molybdenum specimens were tested in torsion over a wide range of temperatures at three widely separated strain rates, and the temperature for onset of embrittlement was determined. Characteristic of body-centered cubic metals and closely associated with plastic deformation is the appearance of a sharp upper and lower yield point. Theoretical explanation of the yield point in iron and low-carbon steel is due to Cottrell,8 who attributes the phenomenon to the pinning of dislocations by the formation of impurity atmospheres around the dislocations. These atmospheres tend to lock the dislocations and make them more difficult to move. The stress required to move a dislocation and thereby cause plastic deformation is greatly increased, and thus an upper yield point is observed. In addition, theoretical analysis,9 as well as experimental observations, show that the upper yield point is strongly a function of temperature. The upper yield point is observed to decrease with an increase in testing temperature, and above a certain temperature (-700° K in iron) it no longer appears. This is consistent with the concept that thermal vibrations will help free a dislocation from its atmosphere, so that the external stress required to free a dislocation from its pinning atmosphere decreases with increasing temperature. Furthermore, with increasing temperature the equilibrium concentration of impurity atoms around a dislocation decreases exponentially with the result that the dislocation is less firmly pinned. In Cottrell's theory of yield point a static model is visualized in which the pinning atmospheres, particularly interstitial atoms, are immobile, and the dislocations are anchored to stationary positions in the lattice. However, experiments1,7 show the upper yield point to be time-dependent or a function of the rate of straining, a high strain rate causing a high upper yield point. Present theory does not adequately account for the rate dependence of the yield point, and the exact function of the interstitial atom is not under stood. Nevertheless, observation of the temperature dependence and rate dependence strongly suggests that the upper yield point phenomenon is due to the interaction between dislocations and pinning atoms, and that a diffusion mechanism is important in determining the yield point.

Jan 1, 1962

By P. A. Tucker, C. R. Hudgens, D. E. Etter, D. L. Roesch, D. B. Martin

The equilibrium phase diagram of the Pu-Cd system is presented based on data obtained by differential thermal analysis, metallography, and electron-microprobe X-ray analysis. Liquidus temperatures range from 320° to 934°C. The system contains one congruently melting compound, PuCd, (945°C), and three incongruently melting compounds, PuCd, (800°C), PuCd, (730°C), and PuCd11 (410°C). A liquid-miscibility gap extends from 2 to 60 at. pet Cd with the monotectic reaction isotherm at 910°C. INTEREST in the potential use of plutonium alloys as reactor-fuel materials has prompted investigation of the phase equilibria in plutonium binary systems. A cursory investigation of the phase equilibria in the Pu-Cd binary system was conducted by differential thermal analysis (DTA), metallography, and electron-microprobe X-ray analysis (EMX). Extensive solid solubility of cadmium in both e and 6 plutonium was predicted1 based on atomic radii and electronegativities. Liquid immiscibility between these two elements was also predicted based on Mott's extension of Hildebrand's method. In the only previous investigation of the Pu-Cd system,2 two intermetallic compounds, PuCd11 (incon-gruent melting point 406°C) and PuCd8, were identified. EXPERIMENTAL The plutonium metal used in this work had a total impurity content of 500 ppm; the major impurities were: carbon (215 pprn), silicon (75 ppm), iron (60 ppm), nickel (40 ppm), and aluminum (25 ppm). The cadmium was reagent grade with a purity of 99.99 pet. The DTA technique for the study of plutonium alloys was previously described in detail.3 The alloys to be studied were prepared in tantalum DTA specimen capsules which were sealed by inert-gas welding. The alloys were homogenized in the liquid state in these sealed capsules which prevented the loss of cadmium by vaporization. Only the thermal arrests in the DTA heating curves were used to define the transformation temperatures of the system since supercooling affected many of the results during cooling. After the alloys were analyzed by DTA, the same alloys were used for the metallographic studies. Metallographic examinations were conducted in the manner described for plutonium alloys., No reaction was detected between the alloys and the tantalum capsules. Alloys for EMX analysis were placed in metallographic mounts together with specimens of unalloyed plutonium and cadmium which served as standards. The samples were highly polished but unetched. No protective coatings were applied to the surfaces of these radioactive specimens. Such coatings are detrimental to the excitation conditions and have been found to be unnecessary for the control of radioactive contamination. RESULTS The results of the DTA studies are presented in Table I. The phase diagram, constructed from these data plus the metallographic and EMX results, is presented in Fig. 1. The congruently melting compound, PuCd2, was identified by the occurrence of a maximum melting point (945°C) at 33.3 at. pet Pu-66.7 at. pet Cd and by the presence of a single phase in this composition.

Jan 1, 1965