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By John Wulff, J. H. Hollomon

THE opinion has been widely held that the corrosion of alpha brass occurs by the selective solution of zinc. As late as 1939, Fink1 and Evans2 suggested that in the initial stage of the corrosion the selective solution of zinc produces copper-rich areas, which subsequently act as cathodes that facilitate the deposition of copper. Previously Abrams3 had shown that most of the copper found on corroded brass was redeposited and not residual, although he did not consider the nature of the initiation of the corrosion process. Enough data exist to indicate that any metal surface is sufficiently heterogeneous to provide the anodes and cathodes necessary for the initiation of corrosion.4,5 Thus, for alpha brass we need postulate not an initial selective solution of zinc, but only the existence of local differences in electrochemical potential. The heterogeneity responsible for potential differences may arise from oxide and other films as well as from alloy concentration gradients. Even though selective corrosion may be possible in some alloy systems, previous data on alpha brass as well as the experimental work reported in this paper do not require this supposition. Bengough and May,6 in a discussion of Abrams' paper, first suggested the addition of small amounts of arsenic (0.03 per cent) to alpha brass to prevent the redeposition of copper (dezincification). This suggestion was later substantiated by Nixon.7 In their studies of the inhibiting influence of arsenic, Evans and Fink were led to the selective-solution hypothesis in order to explain the initial corrosion of such alloys. They believed that an arsenic film covered anode areas and prevented the formation of copper-rich spots capable of acting as cathodes for the deposition of copper. They did not consider, however, the mechanism by which the arsenical film was formed. Bengough and May,8 in another publication, suggested that the commonly found gray or black arsenical film may act to: (I) carry oxygen to the brass surface, (2) increase the discharge potential of copper on brass, (3) precipitate cuprous chloride from colloidal suspension in chloride solutions. Masing9 assumed that the film found upon arsenical brass was metallic arsenic. His measurements of hydrogen overvoltage of bulk arsenic led him to believe that the inhibition of dezincification occurs because the overvoltage of a brass surface is lowered by the arsenic film. He reasoned that this film would permit the more rapid reduction of hydrogen at the cathode, which would prevent the redeposition of copper. In a recent paper,10 we have pointed out that the film formed during the corrosion of arsenical brass and copper in stagnant solutions is essentially arsenious oxide (As203),

Jan 1, 1942

By A. Long, A. Silverman, J. L. Kulp

Garth Crosby has written an excellent geologic description of the deposits surrounding the Gem stocks in the Coeur d'Alene district. The ore deposits in the area of the Gem stocks may hold the key to the age and mineralization history of the entire Coeur d'Alene district. A recent isotopic study10 of the Coeur d'Alene district in this laboratory illustrates that a classical geologic interpretation of these deposits, with its implications for the whole district, may lead to erroneous conclusions. For this reason it seems pertinent to submit a summary of these results and an interpretation of the mineralizing history of the Coeur d'Alene districts. Pitchblende from the Sunshine mine has been dated as 1100-1200 million years (m.y.) by Kerr and Kulp,11 and Eckelmann and Kulp.12 This pitchblende is known to predate the major sulphide introduction in the Sunshine mine, but it clearly follows the metamorphism and folding of the Belt Series. Recently, Goldich (personal communication) dated sericite from the Belt rocks as 1200 m.y. by the potassium-argon method. This date establishes a minimum Belt age if the sericite is of metamorphic origin and a maximum age if detrital. The Belt Series, therefore, is not latest Precambrian. Lead isotope ratios of galenas have been measured and model ages calculated by Bate, et all3 for the Sunshine mine, Farquhar and Cummingl4 or the Bunker Hill and Sullivan mine, and Cannonl6,18 for a few other deposits in the district. Galenas from similar deposits in Southern British Columbia have been measured by Bate, et al,23 Farquhar and Gumming,11 and Wanless and Leech." The new work in this laboratory includes leads from ten widely scattered mines north and south of the Osburn fault, and through a vertical distance of over 5000 ft (Star mine). Included in this group are the Hercules, Sunset, and Mountain Goat mines, which are adjacent to the Gem stocks. In addition, galenas from stringers which cut the Gem stocks in the Success and Sunrise mines and the Hercules hanging wall dike in the lower western portion of the Hercules mine, were included in the study. All of the above leads, except one, give model ages of 1300-1400 m.y. for the time of segregation from the parent material. The concordance of the common lead and U-Pb ages, the great horizontal and vertical uniformity of the lead ratios, the sulphur ratios of two Sunshine mine galenas and three galenas from the Edith, Page, and Hercules mines indicating average crustal sulphur, and the U23/Pb204 ratio inferred for the original lead environment, indicate that the entire mineralization of the Coeur d'Alene-British Columbia base metal belt was derived from a deep source and emplaced in the Precambrian. One sample of galena from sulphide stringers cutting the North Gem stock at the Sunrise Prospect mine gave a modern (i.e., Tertiary) lead ratio. This mine is located at the northern tip of the stock. The presence of modern lead suggests mobilization of some rock lead during the intrusion of the Gem stocks and their outliers. Larsen et al.l8 have dated the Gem stocks as Tertiary by the lead alpha method. If Coeur d'Alene mineralization was genetically related to Tertiary magma formation and intrusion

Jan 1, 1961

By L. Leibowitz, M. G. Chasanov, L. W. Mishler

A drop calorimeter system is described for use in measuring enthalpies to 3600°K. Data are presented for tungsten between 2800" and 3600°K. The enthalpy of tungsten in cal per mole between 2000° and 3600°K can be represented by the equation HºT- Hº298 = - 1.7622 X 103 + 5.7772T + 8.9861 where T is in degrees Kelvin. A tabulation of com -puted values is presented for heat capacity, entropy, and free energy function. A drop calorimeter has been constructed to carry out enthalpy measurements at temperatures to 3600°K. Samples are heated by induction1 and dropped into a commercial adiabatic calorimeter, modified for this purpose. The experimental temperature is limited by the melting point of container materials and compatibility of the container and its contents. Several high-temperature drop calorimeters have been described in the literature1-5 but none has been used at temperatures as high as those in the present work; our measurements of the enthalpy of tungsten range from 2800" to 3600°K. DESCRIPTION OF EQUIPMENT An overall schematic view of the equipment is shown in Fig. 1. Power for the induction coil is supplied by a 25-kw 250 kHz Ther-Monic generator coupled to an iron core RF transformer. The Sample capsule is suspended in the work coil by 10-mil diam tungsten wires which are wrapped around a horizontal 5-mil diam tungsten wire. The horizontal suspension wire is clamped between two massive copper electrodes which are fixed in an x-y motion device that allows adjustment of the position of the heated capsule from outside the vacuum chamber. The copper electrodes are connected by flexible copper straps to a 1250-joule (5 kv, 100 pfarad) condenser bank. When it is desired to release the capsule, the condensers are discharged through the horizontal suspension wire causing it to vaporize rapidly. Very reliable and precise release of the capsule is achieved in this manner. Experiments have shown that no heat correction is required for this discharge energy. As part of the temperature measuring system, two prism holders have been incorporated in the apparatus. The upper prism holder is in the main vacuum chamber itself, whereas the lower one is in a side arm attached to the drop tube below the gate valve. The upper prism is mounted on a rotary vacuum feed-through, and may be moved under a protective shield when not in use. This prevents deposition of vapors on the prism surfaces when temperature measurements are not being made. Similarly, the lower prism is mounted on a push-pull vacuum feed-through, and when not in use may be pulled into its side tube. The prism mountings are fitted with guides and stops so that they may be moved precisely into the desired position. The aim throughout is to minimize the time the prisms are exposed to vapors from the hot samples. At the high temperatures reported in this paper, only the lower prism was used. The upper prism holder in these cases was fitted with an additional radiation shield. By using a prism and viewport, the lower surface of the samples can be observed by an optical pyrometer. The measurements discussed in this paper were obtained with a Leeds and Northrup 8622-C-S series manual pyrometer which is estimated to be accurate to 0.5 pct. Pyrometer calibrations and prism and window corrections were carried out in the conventional manner6 using tungsten strip lamps calibrated by the National Physical Laboratory, Teddington, England. Prism corrections were rechecked after each use. All work to date has been done in vacuum, and no measurable change has been observed in the prism correction below -2300°K for the upper prism and below -2800°K for the lower one. The total time of exposure of the prisms is about 50 sec per run. At high temperature, the final temperature reading is corrected by using the final A value for the prism; see Ref. 6 for details of this procedure. The calorimeter is a modified Parr Instrument Co. (Moline, lll.), Series 1230 adiabatic calorimeter with automatic jacket control. Other authors5 have used a similar calorimeter with good results. The calorimeter jacket cover and calorimeter cover are attached to the drop tube which contains a radiation shield. This shield is a gold-plated copper disc which can be operated manually from outside the calorimeter. The receiver is attached below the radiation shield and is lined with tungsten. In a typical experiment, the calorimeter and its jacket water temperatures were adjusted to 0.000°K temperature difference. The sample was allowed to equilibrate in the furnace at the desired temperature for about 20 min. The initial calorimeter temperature was then recorded, the sample dropped, and appropriate shutters closed. After about 3 min, the drop tube and receiver were filled with helium to 60 torr. The final calorimeter temperature was recorded after it had remained constant over a 5-min period. The equilibration time in the calorimeter was about 25 min. Thermistor probes are used to operate a hot and cold water supply system to maintain the jacket temperature equal to the calorimeter temperature. For actual measurements of the calorimeter temperatures, a quartz thermometer was used (Hewlett Packard Dymec Thermometer, Model #2801A). This thermome-

Jan 1, 1970

By Everett D. Jackson

The largest deposits of chromite in the United States occur in tabular layers in the lower part of the Stillwater Complex, Montana. Nearly 900,000 long tons of chromite concentrates have been produced from mines and mills in this area, and reserves equivalent to more than 2,500,000 long tons of Cr2O3 remain in the ground. Layered concentrations of chromite (known as chromitite zones) occur only within olivine-rich layers of the Peridotite member of the Ultramafic zone of the Stillwater. As many as thirteen chromitite zones, lying conformably one above another, have been found, but only five of them are thick enough to be of any conceivable economic interest, and only two of them have been mined to date. Individual chromitite zones can be recognized by their distinctive internal character and by their stratigraphic position in the Peridotite member. The chemical composition of chromite varies consistently between and within the different chromitite zones. The zones range in thickness from about an inch to more than 12 feet, and the Cr2O3, content of their chromite ranges from 36.6 to 49.2 weight per cent. In any given area, the G chromitite zone is the thickest, but the chromite of the H chromitite zone has the highest grade. Laterally, the thickness of the chromitite zones is related to the thickness of the Peridotite member; in general all are thicker in the eastern part of the Stillwater than in the western part.

Jan 1, 1968

By H. H. Stout

In the early fall of 1925, the writer was conducting, in the Ledoux and Co. laboratory, New York, experiments directed toward ascertaining the effect on its impurity content when cathode copper was subjected to a current of various gases at an elevated temperature below the melting point. The apparatus consisted of a vertical I-in. dia. silica tube about 12 in. long, heated on the outside. The cathodes were broken to pass 3/8-in. mesh, and a current of various different gases was passed up through a 4-in. long column of these loose cathode particles in the vertical tube furnace. Temperature was maintained to 1500º to 1600ºF. and the gas treatments lasted from 3 to 6 hr. The writer observed that whenever reducing gas (H2 or CO) was used, these cathode particles stuck together at points of contact with each other. The cohesion was so marked and tenacious that an examination was made of the fractured surfaces, when cathode particles were broken from the cluster. Crystal growth was always found to have taken place across the surfaces where separate particles were in contact, but only after all oxides, sulphates, etc., had been completely removed. The idea of a possible new process was then conceived and was disclosed to A. M. Smoot (V. P. Ledoux and Co.) with intent to obtain his views. The first conception as given Smoot was "to gas-clean broken cathodes, put them in an extrusion press, solidify and extrude them at around 1500ºF." Smoot's reaction, after a few moments considera- tion, was, "It looks perfectly all right to me.'' The writer and his assistants, W. H. Osborn and H. H. Stout, Jr., after conferring as to ways and means, decided to go ahead with preliminary laboratory experiments, which, it was thought, would move the new process from the possible to the probable. This program followed a course indicated by three basic considerations: 1. Since brittle cathodes were often unintentionally produced, it seemed probable that the laws controlling this type of deposition could be ascertained. 2. We had already proved the gas-cleaning feature. 3. There remained to prove: whether a sound, homogeneous metal billet could be produced with crystal growth established over the entire surface of each individual particle in the billet; and, if so, what would be the physical properties? Osborn arranged with Columbia University for conducting experiments in its research laboratory to prove or disprove the third item; Columbia assigned C. A. Phillipi, Jr. to assist in the project. A press with a cylinder 2 in. high and of I-in. dia. was used. It was surrouilded and heated by a resistance coil 01 Nichrome wire. Broken tough cathodes were used. Experimental Procedure The first run took place March 18, 1926. The resistance wire gave out when temperature of 1000ºF. was obtained. Pressure was immediately applied: perceptible ram movement stopped when 39,000 lb. per sq. in. on the copper was reached, with a maxi-

Jan 1, 1941

By A. N. Rogers

Jan 1, 1883

By Charles L. Elliot

Data on mining applications of geophysical activity in the Free World in 1964 have been made available to SME again this year by the Society of Exploration Geophysicists. Worldwide data were collected as part of an annual service to the mining industry by the Committee for Geophysical Activity of SEG. Data are taken from 245 voluntary responses (53%) to questionnaires circulated to 463 company, government and university organizations engaged in mining geophysical operations and research all over the world. WORLD ACTIVITY Worldwide manpower utilization totalled 9323 professional man-months and $14.5 million was reported spent in mining geophysical activity in 1964. This is up from 9078 man-months and $12.6 million in 1963 and 8065 man-months and $12.8 million in 1962. Worldwide geophysical activity in terms of manpower utilization and expenditures is presented in the accompanying table.

Jan 9, 1965

||Abad, Leopoldo F, Min Engr, Div of Mines, Bureau of Science Manila, P I '23 Abadilla, Quirico A, Geol , Logo Pet Corp Box 172, Maracaibo, Venezuela '20 ||Abarquez, Ramon F, Met, Bureau of Science Manila, P I '24 ||Abbey, Robert Graham, Student, Case School of Applied Science Cleveland, Ohio '21 Abbott, A N , Mines Supt, Mazapil Copper Co, Ltd Concepcion del Oro, Zac , Mexico '23 Abbott, Clarence E , Mgr, Mines & Quarries, Tenn Coal, Iron & R R Co. 1242 Brown Marx Bldg, Birmingham, Ala '04 Abbott, Louis Benjamin, Chief Engr, Consolidation Coal Co, Elkhorn Div Jenkins, Ky '15 Abbott, Robert R , Met Engr, Peerless Motor Car Co Cleveland, Ohio '12 ||Abbott, Wells Osborn, Ray Consolidated Copper Co Hayden, Ariz '23 Abeel, George H., Jr, Cons Min Engr 4612 W 17th St, Los Angeles, Cal '18 Abel, Albert E , Asst to Pres , Valley Mould & Iron Corp Sharpsville, Pa '19 Abernathy, George Elmer, Prof of Geol & Min , Kansas State Teachers College, Pittsburg, Kan '20 Abey, Hiroshi, Min & Met Engr, Chief Engr, Takata Min Co, 2 Yeirakucho, Nichome, Kojlmachiku, Tokyo, Japan '17 ||d'Ablamg, Philip R , Millman, Old Dominion Silver-Lead Co Ellensburg, Wash '25 Aborn, R H, X-Ray Metallographic Research, Mass Inst of Tech Cambridge, Mass '19 Abouchar, Sylvain Sley, Min Engr & Geol, care of S H Sekaly, 13 Rue El Nimr.

Jan 1, 1923

By Freeman Bishop

The Bureau of Mines, beset by political woes not of its own making, is struggling to maintain equilibrium as Congress is being made the focal point for repeated charges that the Bureau has "not done a very good job" of setting up and supervising coal mine health and safety standards approved last year by the Congress. Senator Harrison Williams (D- N.J.) is the latest to enter the arena. A crusading legislator, he is now calling for "legislative overview" hearings to judge Bureau competency in matters of coal safety legislation enforcement

Jan 1, 1970

By GORDON H. FISHER

During the year 1945, the drilling pace in West Texas increased above that in the year 1944, and represented the highest number of well completions since 2941. The 1680 new wells drilled 8,287,958 ft. of hole for a per well average of 4933 ft. This depth is approximately 30o. ft. deeper than the average for the year 1944. Although the deepest well drilled in West Texas (Phillips Petroleum Company's Ada Price No. 1, in Pecos County) was completed during the year. 1944 to a depth of 15,279 ft. and tested the Ellen-burger horizon, the producing depth record for West Texas was set during the year 1945 with the completion of Amerada Petroleum Corporation's Jones No. I-A, in the Jones Ranch field, Gaines County, which now is producing at 11,422 ft. from the Devonian formation.

Jan 1, 1946

By T. J. Koppenaal, M. E. Fine

A yield point effect attributed to short-range ordevi?g (SRO) occurs in Cu base Al. At at 296°K varies with heat treatment, decreasing as the annealing ternperature is raised .from 433Oto 598°K. Davies aid Cahn' observed a corresponding decrease in SRO. (523 °K anneal, measured at 77°K) is approximateZy proportional to the variations of A7 with strain rate and testing temperature are also Consistent with the idea that is associated with SRO. A preliminary investigation of the tensile properties of a Cu-Al single crystals showed the presence of a rather strong yield-point effect (drop in flow stress after initial yielding). The object of this research was to investigate its origin and behavior. a Cu-Al alloys are particularly interesting because diffuse X-ray scattering measurements by Davies and Cahn,' Houska and Averbach,' and Borie established the presence of short-range order. The degree of local order may be changed with heat treatment.' cottrel14 suggested that the presence of local order might result in a yield-point effect, and thus the possibility exists here for experimentally ascertaining the importance of short-range order with respect to yield points in these alloys. Since a 12 pct difference exists between the atomic sizes, elastic or Cottrell locking5 must also be considered. Further, Howie and swanne have shown that the stacking fault energy of copper is reduced by aluminum additions. The width of extended dislocations should thereby increase. hus the conditions appear attractive for Suzuki locking.' Finally, the possibility of stress-induced order at dislocations, schoeck locking,' must also be examined, EXPERIMENTAL PROCEDURE Alloys up to 14 at. pct Al were prepared by induction melting high-purity (99.999 pct) Cu and (99.996 pct) Al in a graphite boat under a dynamic vacuum of 5 X 10o mm of Hg. After homogenizing the ingots at 900°C for at least 24 hr under vacuum, they were rolled with intermediate anneals to strips 1.55 mm thick. Single crystals 10 in. long were grown by lowering strips, contained in a split graphite mold sealed in fused quartz at 5 X lo-' mm of Hg, through a single coil induction heater at a constant rate of 1/2 in. per hr. Tensile specimens 1.25 in. long were cut from the single crystal strips and reduced cross sections about 0.7 in. long and 3.0 to 3.5 mm2 in area were introduced by filing and abrading.8 To remove the worked portion about 10 pct of the cross-sectional area was removed by etching. Back-reflection Laue photographs of a filed and etched specimen were taken before and after annealing at 900°c for 24 hr. Small, well defined Laue spots were obtained with no visual difference in the two photographs. Further, specimens with and without the reduced sections began yielding at about the same stress. Hence, for our purposes, filing and abrading did not affect the structure of the specimens. Each single crystal specimen was annealed at 900° c in vacuum for at least 24 hr and furnace cooled; while cooling through the range of 250o to 200°c, the rate was about 55°C per hr. Orientations were determined by the usual back-reflection Laue

Jan 1, 1962

The Goodman Mfg. Co., Chicago, builders of underground electric mining machinery, celebrated its 50th Anniversary on April 23rd. The company has a complete line of cutting machines, loaders, conveyors, locomotives, and shuttle cars for service in both coal and metal mines. The Joy Mfg. Co. has received, under the provisions of the Economic Cooperation Administration, an initial order in excess of $1,000,000 for equipment to be used in the mechanization of iron ore mines in France. While the equipment will be used in various privately owned mines, the order was placed through the French Society for the Development of Mechanical Mining. Included in the equipment are the company's recently developed hard rock loaders and shuttle cars. American Brake Shoe Co. has consolidated all operations of its Canadian subsidiaries into one corporation, the Dominion Brake Shoe Co. Ltd., Montreal, Canada. The products of Dominion Brake Shoe include brake shoes, track equipment, manganese steel castings, automotive brake lining, air compressors, and paint spray equipment. Exhibits of more than 2000 electrical products, processes, and techniques, ranging from precise aircraft instruments to complex working models of steel mill, textile and other industry equipment, will be displayed in the "More Power To America Special" when it makes its nationwide tour this spring. C. H. Lang, Vice-President in charge of sales for General Electric's apparatus department, said that the train will visit the country's key industrial centers for inspection by utility and industrial executives and municipal leaders. The train will be hauled by an Alco¬G-E two-unit, 4000-hp., Diesel-electric locomotive which in itself will be part of the unusual series of displays. Sizing of Excavators and Hauling Equipment. The Power Crane and Shovel Association has released a 24-page bulletin dealing with the proper sizing of excavators and hauling equipment, Technical Bulletin No. 3. Rubber Conveyor Belting. "Installation, Care and Maintenance of Rubber Conveyor Belting" is the title of a booklet just published by the Carlyle Rubber Co., New York. Power Transformers. The manufacturing procedure of Allis-Chalmers small power transformers is described in a new 28-page bulletin, 61B6094A, covering the core and coil unit, no-load tap changer, tank construction, cooling methods, oil preserving systems, bushings, terminal compartments, indicators and testing of transformers. Safety Equipment. General Scientific Equipment Co., Philadelphia, has released a 46-page, fully illustrated catalog on personal protective equipment and industrial safety devices. This new catalog covers respiratory devices, eye protection, hats, gloves, carboy pumps, drum pumps, and miscellaneous safety equipment for use in mines, industries, etc. Osmosalts. The Osmose Wood Preserving Co., Buffalo, N. Y., has issued a bulletin on Osmosalts, the wood preservative which, say the manufacturers, makes timber last three to five times longer, slashes maintenace costs, stops rot, and resists wood-destroying insects. Jigs. The Dorr Co. has acquired the Pan American jigs and they are now known as the Dorrco-Pan American jigs. Originally developed as a gold-saving device for dredges, the simplicity, ease of operation. efficiency, and negligible maintenance of these jigs have resulted in wide adoption on all types of placer operations, in the closed grinding circuits of gold mills, and on many applications where a coarse bed concentrate is separated from the ore gangue.

Jan 5, 1950

By W. T. lsbell

HERCULANEUM, MO., about thirty miles south of St. Louis on the Mississippi River, is the site of the lead smelter of the St. Joseph Lead Co. The lead concentrates come by rail from the Flat River district and from three properties in Madison County, Missouri; from the Balmat division in St. Lawrence County, New York; a small tonnage from the Tri-State district; and occasionally from the Aguilar property in Argentina. The average grade is 67 to 68 percent lead and 1 to 3 oz of silver. The bulk of the material is flotation concentrate, with some gravity or table concentrate. No secondary metals, outside drosses, or any materials high in bismuth, arsenic, or antimony are treated. All concentrate is received in box-caps and is unloaded directly from a trestle into the concentrate bins at the roaster plant. Flux, coke, and any miscellaneous lead-bearing material is either unloaded directly into bins or unloaded with a locomotive crane. All moving and switching of cars is done with two thirty-ton steam locomotives. Shipping facilities for the plant are provided by the Missouri-Illinois Railroad. Water for the plant and for fire protection is obtained from a dam built in a near-by creek. Drinking water both for plant and town is obtained from

Jan 1, 1947

By John H. Hollomon

The interpretation of notched-bar impact results has been a matter of controversy since the introduction of more or less standard tests by Fremont,' Charpy2 and others at the turn of the century. Many investigators3-l1 have contributed to the understanding of the significance of such tests. Several symposiums12,13 have been held with the express purpose of discussing the significance and interpretation of the impact tests. It is not the purpose of this paper to review all these contributions to the development of the knowledge on this subject, but rather to present an interpretation of notched-bar impact tests that appears to be in agreement with the available published data. Fundamentally, the interpretation discussed in this paper of the brittle failure of some steels in notched-bar impact test is similar to the qualitative analysis presented by Ludwik3 in the I92o's. Essentially, Ludwik stated that the function of the notch was to increase the tensile stress necessary for yielding, and that brittle failure occurred when the stress necessary for yielding exceeded the normal stress required for fracture (with no plastic deformation). Ludwik, however, had no means of measuring this normal stress necessary for failure of a plastically* undeformed metal, therefore he could not extend his interpretation beyond the qualitative stage. Kuntze14 and recently Mc-Adam15 attempted to determine the effect of deformation on the stress necessary for fracture by testing, in tension, specimens notched to various depths and angles. Because of the uncertainties in Kuntze's (and McAdam's) analysis of the stresses (which have been pointed out by Sachs16) and the inherent nonuniformity in the stress distribution in notched bars, the results of such investigations are difficult to interpret. A more direct method of measuring the effect of deformation on the fracture stress was suggested in previous papers"-18 and has been utilized in the present investigation. The present paper concerns itself primarily with the behavior of notched impact specimens. The effects of strain rate, temperature, and stress distribution, which are discussed with reference to the impact specimen, apply just as well to the behavior of metal at the bases of notches in any engineering structure. All that is necessary is to determine the stress distribution in the structure at the base of the notches.

Jan 1, 1944

By John H. Hollomon

The interpretation of notched-bar impact results has been a matter of controversy since the introduction of more or less standard tests by Fremont,' Charpy2 and others at the turn of the century. Many investigators3-l1 have contributed to the understanding of the significance of such tests. Several symposiums12,13 have been held with the express purpose of discussing the significance and interpretation of the impact tests. It is not the purpose of this paper to review all these contributions to the development of the knowledge on this subject, but rather to present an interpretation of notched-bar impact tests that appears to be in agreement with the available published data. Fundamentally, the interpretation discussed in this paper of the brittle failure of some steels in notched-bar impact test is similar to the qualitative analysis presented by Ludwik3 in the I92o's. Essentially, Ludwik stated that the function of the notch was to increase the tensile stress necessary for yielding, and that brittle failure occurred when the stress necessary for yielding exceeded the normal stress required for fracture (with no plastic deformation). Ludwik, however, had no means of measuring this normal stress necessary for failure of a plastically* undeformed metal, therefore he could not extend his interpretation beyond the qualitative stage. Kuntze14 and recently Mc-Adam15 attempted to determine the effect of deformation on the stress necessary for fracture by testing, in tension, specimens notched to various depths and angles. Because of the uncertainties in Kuntze's (and McAdam's) analysis of the stresses (which have been pointed out by Sachs16) and the inherent nonuniformity in the stress distribution in notched bars, the results of such investigations are difficult to interpret. A more direct method of measuring the effect of deformation on the fracture stress was suggested in previous papers"-18 and has been utilized in the present investigation. The present paper concerns itself primarily with the behavior of notched impact specimens. The effects of strain rate, temperature, and stress distribution, which are discussed with reference to the impact specimen, apply just as well to the behavior of metal at the bases of notches in any engineering structure. All that is necessary is to determine the stress distribution in the structure at the base of the notches.

Jan 1, 1944

THE slag performs two useful functions. in open-hearth steel-making. First, it is the means of disposal of all the impurities, save carbon, which are removed from the charge materials in refining the steel, so it must be suited to receiving and retaining as much as possible of undesirable elements with minimum loss of iron and useful alloying elements. Second, the slag serves as a buffer between the flame and the bath and transfers oxygen to the metal at a measured pace contrasted with the violent and difficultly controlled oxidation of the bessemer process. At the same time, the slag is a thermal insulator that limits the rate at which heat can be delivered to the metal from the flame, and a heavy slag blanket thereby serves as a brake on production rates. It has been said with justification that the secret of good steel- making is to make a good slag and the steel will take care of itself. In a broad sense, the subject of slag control includes not only the adjustment of the composition of the slag but also of its relative weight in terms of percentage of the metal-bath weight. The slag is made up essentially of: (1) oxides formed by oxidation of silicon, manganese, phosphorus, and iron in the charge, (2) SO2, MnO, MgO, and other oxides charged as such or introduced incidentally with ores or fluxes or by refractory erosion, and (3) lime charged or fed to the heat to neutralize the "acidic" oxides present (SiO2 and P2O5). Obviously, if practically perfect control were possible over the composition of the charge as well as over the oxidation process during the melting period, both slag weight and composition would be very nearly predetermined, and the control problem would be solved. Unfortunately, only a somewhat imperfect control over these factors is possible, so the operator must begin during the lime boil and continue through the refining period to discover and correct departures from the normal pattern of slag development. To do this as the heat progresses, the first helper must be able to make quick estimates of the composition and physical state of develop-

Jan 1, 1951

By Herbert Hoover

YOUR committee asks that I speak today on the relations of the engineering profession to public affairs. That takes in a lot of ground. This being a cheerful occasion, I will assume that I should exclude the engineer's function as a taxpayer. This being a nonpartisan occasion, I will assume that I should not refer to his voting emotions in 1940. Perhaps what was in the minds of your committee was the application of engineering thought to the confusions of the times. That is also a lot of ground. I fear, however, its boundaries disappear in mirages and rainbows on all sides. Now any entry of the engineer into public affairs involves his breaking into the fields of the sociologists, the economists, and the politicians. However I don't know why, seeing the difficulties these professions are having, they should not welcome a little help.

Jan 1, 1939

By B. Chalmers, L. Bäckerud

The growth temperature of dendrite tips has been measured in a binary alloy system, Al-Cu, as a function of rate of formation of solid phase. Metallographic examination has rerealed the dendritic structure dereloped during different stages of the freezing process and factors influencing the undercooling, such as solute buildup, surface tension, and kinetic effects, have been estimated. Practical implications of the results are discussed. THE development of a dendritic growth pattern during the solidification of metals and alloys has an influence at least equal to that of grain size on the properties of the casting or ingot being produced. and consequently much interest has been devoted to the study of this phenomenon. A review of the knowledge gathered up to 1964 has been given by Chalmers.' Among recent publications in the area the works of Jackson et al 2 and Flemings and his coworkers3,4 are of special interest. This work is an experimental study of the factors which influence the development of a dendritic pattern during the solidification of a typical binary alloy system, A1-Cu, when there is no heat source in the liquid. This means that the temperature and the temperature gradient are controlled by the heat extraction from and latent heat evolved by the growing crystals. EXPERIMENTAL PROCEDURE Samples were prepared from a master alloy made up of aluminum, 99.995 pct, and copper. 99.99 pct, of the concentrations given below and of sufficient size to fill cylindrical graphite molds of 35 mm ID and 35 mm height. Bottom. wall. and lid of the graphite molds were all of 6 mm thickness, Fig. 1. Thin ceramic thermocouple shields could be introduced at different positions in the sample through holes in the lid. The assembly was heated in a small vertical resistance furnace to a suitable temperature. 700° to 720°C. which is well above the melting point of the sample. It was thereafter taken out of the furnace and chilled at selected rates, and the temperature changes in the sample were recorded. For high sensitivity in the temperature recordings, a reference thermocouple was held in a solidifying pure aluminum melt. which was very well insulated and therefore was at a constant temperature. 660°C, for nearly half an hour. The thermocouples were connected so that the difference voltage was fed into the recorder of which the most sensitive range was 1 mV. Temperature variations could be read to within 0.l°C. The thermocouples used were of the Chromel-Alumel type (28- or 38-gage wires) and the recorder a two-pen Moseley strip chart recorder. The different rates of chilling were obtained in the following way. a) The graphite crucible was wrapped in one or two layers of an insulating. feltlike material (Fiberfrax paper from the Carborundum Co.). The drop in temperature per unit time after complete solidification could thereby be varied from 8" to 18°C per min. This corresponds to a rate of heat extraction in the given samples from 0.08 to 0.17 cal cm-' sec-I. 6) The bare graphite mold was placed free on a piece of firebrick. The measured temperature drop was around 50°C per min (-0.5 cal cm-" ' sec- I). c) By blowing compressed air through a tube with many holes surrounding the mold in a ring shape. the rate of heat transfer could be raised to 150' to 200°C per min (-1.7 cal cm-3 sec- I). d) Cooling rates around 1000 C per mill (-9.4 cal cm-3 sec-l) were obtained by substituting the air in the device used in c by water. The range of cooling rates used in these experiments correspond to technical casting processes from slow solidification as obtained in sand molds to very rapid freezing which occurs in some continuous casting and welding processes. EXPERIMENTAL RESULTS The A1-Cu system was chosen for the experiments: the relevant part of the phase diagram is reproduced in Fig. 2. Observation of the Center Temperature. When a thermocouple is inserted in the center of the melt. the type of cooling curves obtained at slow solidification rates differs little from numerous published curves from similar systems. and the solidification pattern

Jan 1, 1970

By A. S. Callen

These iron mines of Spain are located on the mountain ridge forming the boundary between the Teruel and Guadalajara provinces, called Sierra Menera. They form a property of 25 mines extending over an area of 1,677 hectares (4,140 acres) situated at a height varying from 1,200 m. (3,940 ft.) to 1,500 m. (4,920 ft.) above sea level. The deposit follows the direction north to south; huge masses of ore are being found both on the slopes and at the summit of the Sierra. The ore occurs among quartzites and magnesite limestone, in some places overlaid by quartzite 15 m. (50 ft.) thick; in some others (and this is more general) the ore is overlaid by earth and boulders of quartzite origin; this layer is about 8 m. (26 ft.) thick. The ore beds occupy the geological horizon of the Superior Trias or Muschelkask, which are here in direct contact with the Silurian quartzites. The lime-stones have been more or less transformed. There is ample evidence to show that these mines were worked in very ancient times—objects and tools employed in mining by the ancient Romans and Arabs are to be found plentifully in old workinigs which extend down into the deposits. It has been estimated that more than 10,000,000 tons of ore were mined in the old days in this district and carried to the primitive forges in the vicinity where iron of much renown in Spain was extracted. Remains of more than 20 of these forges are found in the neighborhood of Sierra Menera and are usually situated near waterfalls and forests. Much investigation has been carried on for the purpose of determining the quantity of ore to be found in these mines, but no exact calculations can be made at present. When the investigation is completed it will surely be found that the deposit contains a much larger quantity than the 100,000,000 tons indicated by the present workings. The mines are now worked as open quarries and this method can and will be followed for a long time, probably until the deposit is worked out. Figs. 1 and 2 give some idea of the quarries in operation and the reserves, the iron-ore stocks, screening installation and general arrangement. From these quarries 1,000,000 tons can be mined annually (987,000

Jan 1, 1916

By L. H. Schwartz, M. V. Nevitt

THE phase Ti2Ni has been described by Laves and Wallbaum,1 who found the phase to be face-centered cubic with 96 atoms per cell, by Duwez and Taylor,2 who confirmed these observations and reported a lattice parameter of 11.333A, and by Rostoker,' who reported the structure to be isomorphous with the double carbide Fe,W,C, type E93, and to have a lattice parameter of 11.29A. In this study a group of isostructural phases has been found among alloys of certain second and third long-period transition elements. The systems investigated included all the combinations of zirconium and hafnium with the Group VIII elements rhodium, palladium, iridium, and platinum. There is evidence that many of these new Ti2Ni-type phases require oxygen for their stability in the temperature ranges in which they were studied. EXPERIMENTAL PROCEDURE Alloy samples weighing 5 g were prepared by arc-melting metals whose purity is indicated in Table I in a helium-argon atmosphere. Samples of the as-cast buttons, wrapped in molybdenum foil and sealed in evacuated quartz tubes, were

Jan 1, 1959