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CHARLES KIRCHHOFF, Chairman. ALBERT SAUVEUR, Vice-Chair-man. A. A. STEVENSON, Vice-Chair-man. HERBERT M. BOYLSTON, Secretary, Abbot Bldg., Cambridge, Mass. John Birkinbine, J. Esrey Johnson, Jr., Felix A. Vogel, William H. Blauvelt, William Kelly, Leonard Waldo, James Gayley, Richard Moldenke, William R. Walker, Henry D. Hibbard, Joseph W. Richards, William R. Webster. Henry M. Howe, E. Gybbon Spilsbury, Frederick \V. Wood. Robert W. Hunt, A. A. Stevenson is appointed an additional Vice-Chairman of the Committee. He will serve as Acting Chairman during the absence abroad of Professor Sauveur.

Jan 7, 1913

By M. E. Nicholson

The effect of boron on the austenitic transformation rate of iron is smaller than on low carbon steels. The influence of austenitizing temperature on B-Fe is the reverse of its influence on steels. THERE have been many studies made of the influence of boron on the hardenability of steel, but apparently none has been made of its influence on the y-a transformation of pure iron. There are several facts suggesting that boron should have a pronounced effect on the transformation rate of iron. First, Simcoe et a1.l indicated that boron reduces the nucleation rate of ferrite and bainite. Second, they showed, along with others,', " that the lower the carbon content of steel the greater the influence of boron on hardenability. If this trend extends to pure iron, the influence on rate of ferrite formation should be considerably greater for iron than for medium carbon steels. According to Rahrer and Armstrong," the multiplying factor for boron in pure iron should be about 2.40, compared with 1.50 in a 0.35 pet C steel. According to an extrapolation made by Grange and Mitchell,' the effect should be even greater, and the multiplying factor should be about 3.5 in iron. Many investigations of the boron influence'.7, 2, 5 indicated that boron is effective only when in solid solution. On the other hand, Chandler and Bredig" suggested that boron increases hardenability by combining with nitrogen, thereby preventing formation of AlN, which catalyzes the decomposition of austenite. If their hypothesis is valid, boron should have no effect on an alloy free from nitrogen. Digges et al." showed that so far as low nitrogen high purity Fe-C alloys are concerned this is not the case. No experiments, however, have been made on low nitrogen iron. To determine whether or not boron has an effect on low nitrogen iron and, if an effect exists, to determine whether it is as large as predicted from the investigations of boron treated steels, the following work was performed. Because of the rapidity with which iron transforms from austenite to ferrite at even a moderate degree of supercooling, it was decided to study the influence of boron on the transformation rate of iron by determining the effect of quenching rate on the temperature of the beginning of transformation. The technique, essentially that used by Greninger' and Duwez,H consisted of heating small specimens, 0.1 in. sq and 0.010 in. thick, in an atmosphere of purified helium with a resistance heater coil, and then quenching the sample in a jet of helium gas. At the time the jet was applied, the heating coil was removed from around the sample. The sample was suspended in the furnace on 30 gage chrome1 and alumel wires, one welded to each side of the specimen, which also served as a thermocouple for measuring the specimen temperature. Specimens were prepared from vacuum-melted iron obtained from the National Research Corp. which was rolled to a thickness of 0.060 in. and then decarburized in wet hydrogen for 51/2 hr at 700°C. This treatment also removed any boron present in the iron. The resulting iron contained 0.001 pet C. 0.0002 pet N, and 0.005 pet 0. One half of the piece was then boronized by surrounding it with 325 mesh boron powder and heating it for about 2 hr at 900°C in H,. The boronized iron was then homogenized at 1100°C for 24 hr. The iron boride case formed by boronizing was removed by grinding 0.010 in. from each side of the plate, and the piece was finally rolled to a thickness of 0.010 in. The resulting alloy contained

Jan 1, 1957

By William E. Ford, Edward Salisbury Dana

The monoclinic Wolframite Group and the tetragonal Scheelite Group are included here. Wolframite Group WoIframite (Fe,Mn)W04 a : b : c = 0.8300 : 1 : 0.8678 B = 89' 22' Hiibnerite MnW04 048362 : 1 : 0.8668 89' 73' WOLFRAMITE. Monoclinic. Axes a : b : c = 0.8300 : 1 : 0.8678; B = 89' 22'. mm"', 110 A 1TO = 79" 23'. ay', 100 A 101 = 62' 54' at, 100 A 102 = 61" 54'. $', 011 A 011 = 81" 54'. Twins: (1) tw. axis c with a (100) as comp.-face; (2) tw. pl. k (023), Fig. 449, p. 171. Crystals commonly tabular (1 a (100); also prismatic. Faces in prismatic zone vertically striated. Often bladed, lamellar, coarse divergent columnar, granular. Cleavage: b (010) very perfect; also parting (1 a (100), and 11 t (102). Fract,ure uneven. Brittle. H. = 5-5.5. G. = 7.2-7.5. Luster submetallic. Color dark

Jan 1, 1922

Iowa Geological Survey, Des Momes, Ia. George F. Kay, State Geologist A list of publications will be sent upon request Most of the papers of the Survey have been published in the Annual Reports, issued since 1892. Separates of the many papers in the Reports may be had for postage, except where they are out of print, and except for vol 1 (1892), 2 (1894) and 14 (1903), where no separates are to be had. Thirty-five Annual Reports have been issued up to and including vol 35 (1929). A charge, plus postage, is made for vols, 4, 5, 7, 8, 9, 10, 28 and 33, others will be sent free upon request, plus postage on from 2 to 6 pounds Space prohibits giving more than a general picture of some of the contents; vols 4, 5, 7, 8, 9, 10, 11, 12, 13, 15, 16, 20, 27, 32, contain, among others, papers on the geology of Iowa, by counties Vol. 19 (1908), 6 lb , contains a number of papers dealing with the peats and coals of Iowa, and has bibliographies of those subjects Vol 22 (1912), 6 lb , contains an annotated bibliography of Iowa geology Vol-24 (1913), 6 lb , contains the analyses of 16 Iowa coals Vol 28 (1917, 1918), price $1 50, 4 lb , completely covers the subject of gypsum in Iowa, and has a bibliography of the sub¬ject. Each volume carries an administrative report and a review of mineral production for the period covered In addition, Technical Paper 2 (1930), Studies of Iowa coals, will be sent free upon request Also a geological map of Iowa, and maps of Iowa showing the distribution of the glacial drift sheets throughout the state, have been issued and are available

Jan 1, 1933

By AIME AIME

DONALD K. CRAMPTON, present Chairman of the Institute of Metals Division, A.I.M..E., is well known by nonferrous metallurgists in all countries for his research work on the fabrication and properties of copper and its alloys including investigation of season- and stress- corrosion cracking. He is also well known, at least by many metallurgists in the United States for the proficiency with which be carries on his hobbies, in i:lrlditlg photography. gardening, and golf

Jan 1, 1941

By M. Gensamer

A RECENT paper1 described, by means of stereographic pole figures, the preferred orientations produced by cold-rolling low-carbon steel of automobile-body grade. It was found that the surface of the sheet exhibited a deformation texture significantly different from the texture possessed by the inside of the sheet. Efforts to produce the surface texture by buffing a sample exhibiting the normal or inside texture, using a copper lap, have not been successful. In view of the data collected, by Kurdjumow and Sachs2, it was suggested that the surface texture might be the result of partial recrystallization of the normal or inside texture. The recrystallization texture of cold-rolled mild steel was studied by Goss3, but he did not use the pole-figure method, so that his conclusions were in need of verification. For these reasons the work reported in the present paper was undertaken. It had two objectives: (1) to study the general behavior of cold-rolled mild steel on recrystallization below the critical temperature A,, and (2) to attempt experimentally a demon-stration of the genesis suggested above for the surface texture in cold-rolled steel. The material was that used by Gensamer and Mehl, cold-rolled to 97.5 per cent reduction in thickness. Fig. 1 is an X-ray pinhole photo-gram of this material, taken with the beam transmitted perpendicular to the plane of the sheet, using a molybdenum target at 35 kv. with no filter. It is typical of the inside texture, but in it the deformation texture is better developed than in the samples that showed a well developed difference between the inside and surface samples. Specimens from this sheet, which was 0.005 in. thick, were annealed for 5 min. at various temperatures in a lead bath. After about 0.0005 in. had been etched from both surfaces, X-ray photograms were prepared, using the technique described in the earlier paper'.

Jan 1, 1936

By C. Feng

HE sensitivity of twinning in molybdenum alloys containing 20 or more at. pct Re was reported by Dickenson and Richardson&apos; and Sims et a1.&apos; The latter3 also studied the effect of twinning on plastic deformation of these alloys. Recently, in this laboratory, the twinning planes in a series of Mo-Re alloys were successfully identified by tracing their boundaries on two known surfaces of the crystals, with the aid of stereographic projection. The nominal alloy composition and the results of the determination are listed in Table I. Metallic powders of molybdenum and rhenium with 99.9 pct purity were mixed, pressed and arc-melted into buttons under purified argon in a water-cooled copper hearth; the buttons were annealed at 2400 °C in vacuum (10-&apos;mm Hg) for 1 hr, remelted under argon and finally reannealed in vacuum at 2400°C for another hour. This treatment yielded a homogeneous alloy. Large-grain specimens devoid of subgrains were obtained with grain diameter varying from 1/8 to 1/2 in. A typical specimen weighed about 15 g. Orientations were determined by taking X-ray back reflection photographs for each grain on a polished surface of the specimens. Two surfaces were cut and polished; the angle between the two surfaces was measured with an accuracy of *2o. The twins were produced by compression in a hydraulic press at room temperature. Usually, several sets of twins could be obtained within each grain. Except in cases where no twins were formed, (Crystals 7, 8, and 9) the twinning planes were identified consistently as the (112) family over a wide range of alloying compositions and surface orientations of the crystals, as indicated in the stereo-graphic triangle in Fig. 1. The twins, however, were not broad enough to accommodate a conventional X-ray beam and no identification could be made of the twinning direction. Nevertheless, the direction must be one that lies in a plane of symmetry perpendicular to the twinning plane. There are only two such possible planes in a bcc lattice, namely the (110) and the (100) planes. Of these, only the (110) planes are perpendicular to (112), and the <111> direction is the intersection of the two perpendicular planes. It can thus be concluded that <1l1> is the twinning direction. The twinning elements of molybdenum have been reported as the (112) planes and the <111> directions,4 which are also the operative elements in other body-centered-cubic metals, such as W, a-Fe, and ß -brass.5 Thus, the present finding of the twinning elements in Mo- Re alloys supports the concept that twinning formation is mainly governed by the lattice structure. It is of interest to note that for specimens containing 12 at. Pct Re or less, no twins were found after being plastically deformed to as much as 30 pct reduction in height by compression, while for the 35 at. pct Re alloy, twins were formed with less than 1 pct deformation. This, of course, does not exclude the possibilities that for Re-Mo alloys containing 12 pct Re or less, twins could be formed under different conditions, such as at liquid air temperature or under impact loading. The present results, however, suggest that under the same conditions twinning is increasingly sensitive with increasing rhenium content. Consequently, the plastic strain at which twinning starts was found inversely proportional to the amount of rhenium in solid solution with molybdenum. This plastic strain necessary to cause twinning may be used as a criterion in the study of twinning characteristics.

Jan 1, 1961

By J. M. Lommel

DURING an investigation into the effect of heat-treatment on the creep properties of the magnesium alloy ZW1, (1 pct Zn, 0.6 pct Zr), the previously published methods of final polishing were found to be unsatisfactory. A new diamond-polishing technique has been developed to facilitate the study of fine precipitates in this and other magnesium alloys, and is described in this note. The sectioning and coarse grinding techniques are those of Fox and Hall,&apos; and Hess and Cieorge.&apos; Pre- liminary mechanical polishing is done with 6-µ, and 1-µ( grades of diamond compound on &apos;Microcloth&apos; using a lubricant of &apos;Hyprez&apos; oil. When the conventional technique is used with a 1/4- µ diamond wheel for the final polishing of magnesium alloys, scratching is likely to result from the abrasive action of the &apos;Microcloth&apos; nap on the soft metal surface. This problem has been overcome by the use of a cream on the wheel in order to separate the specimen surface from the polishing cloth. To prepare this cream, a solution of 6-ml tri-ethanolamine in 75-ml water is stirred into 12.5 g stearic acid at a constant temperature of 80o to 90°C. The cream is allowed to cool, and is then &apos;whipped&apos; to a smooth consistency with 100-ml &apos;Hyprez&apos; oil. Before polishing, the diamond loaded &apos;Microcloth&apos; is moistened with a few drops of &apos;Hyprez&apos; oil, then a small amount of cream is worked into the nap. For the best results a wheel speed of 500 rpm should be used for polishing, and the specimen should be held by hand with a light pressure while being rotated in the opposite direction to the wheel. After polishing it is necessary to swab the specimen thoroughly in methylated spirits to remove residual cream and oil from the surface in order to avoid uneven etching and drying stains. Fig. 1 shows the surface finish obtained on a specimen by polishing on a 1/4- µ diamond wheel using the cream, and Figs. 2 and 3 the precipitate observed in ZW1 after polishing, and etching for two seconds in nitric acid 15 pct in ethylene glycol. This new diamond-polishing technique has made a valuable contribution to the programme of metal-lographic research on ZW1 and has become a routine laboratory practice for other low alloy content magnesium alloys.

Jan 1, 1961

By T. E. Scott, R. P. Zerwekh

The charactevistics of the deformatiotz of fcc thorium were examined between 78 and 473 K. Activation energy, actiuation volume, and the temperature dependence of the flow stress were determined and conlpared uith several theories for the rate-controlling mechnnistn of the tempemture-dependent component of the flou~ stress. It was established that the Cottrell-Stokes law does not hold, even approximately, for thorium. Through consideration of the above factors and other parameters, it was concluded that the vandom solute barrier theory proposed by Friedel demonstrates the best agreement with experimental observations of the deformation of thorium below ambient temperature. THORIUM, the first metal in the actinide series of rare-earth elements, is interesting and important from two points of view. In the more practical vein, it is a potential reactor fuel. As such, it is important to know its properties. Of specific interest here are the mechanical properties of thorium. Second, no detailed information concerning the deformation characteristics of the actinide elements has been gathered to date. In view of the interesting physical and chemical properties of these metals, their mechanical behavior might reveal characteristics which could improve our understanding of the mechanisms controlling deformation of the more common metals. For example, it has been shown1 that thorium exhibits a yield point which is greatly enhanced by interstitial solute elements such as carbon. This is not a normal occurrence in fcc metals. The goal of this investigation, therefore, was to characterize the deformation of polycrystalline thorium. MATERIAL AND PROCEDURES Thorium, made by the magnesium intermediate alloy process described by Peterson et al.,2 was rolled and swaged to 0.065-in.-diam wire. The metal analysis is given in Table I. After preparation, the oxygen and nitrogen contents had risen to 308 and 60 ppm, respectively. The 0.065-in.-diam wires were cut into 2-in. lengths and annealed in a vacuum of lo-&apos; Torr at 750°C for 1 hr, producing a grain size of 2735 grains per sq mm. The ends of the 2-in. sections were masked off so that a 1-in. gage length could be electropolished. Specimens were polished at 35 v in a solution of 6 pct perchloric acid in methanol which was maintained at 0°C . The gage diameters after polishing were about 0.0625 in. The tests were run on a screw-driven tensile machine at a constant crosshead speed corresponding to a strain rate of 0.005 min-&apos;. The strain rate was changed rapidly after each 0.01-in. extension between 0.005 min-&apos; and one of three higher strain rates which were selected in order to achieve strain-rate ratios of 5, 10, and 20. Tests were run at several temperatures from 78" to 473°K; most were tested at 423", 300°, 215", and 78°K. EXPERIMENTAL RESULTS Flow Stress vs Strain and Temperature. Typical true stress-true strain curves for thorium are shown in Fig. 1 for several temperatures over the range 473" to 78°K. The curves for 78", 215", 300") and 423°K were obtained from strain-rate change tests using the lower (0.005 min-&apos;) or base strain-rate values of stress. Additional tests, using the same base strain rate at different strain-rate ratios, gave curves which virtually superposed on those shown, indicating that strain-rate changes did not materially influence the work-hardening characteristics at the base strain rate. The curves for 273") 373") and 473°K were standard tensile tests at 0.005 min-&apos;. The behavior of the flow stress with temperature is

Jan 1, 1968

ASIDE from the John Fritz Medal, in which the Institute participates through its representation on the John Fritz Medal Board, the Institute itself has three major awards to make annually and one special prize for excellence in technical papers, as follows: The Robert W. Hunt Medal and- Prize, The J. E. Johnson, Jr., Award, the James Douglas Medal, and The Lewisohn Platinum Prize to senior members. ROBERT W. HUNT MEDAL AND PRIZE The partners of Robert. W. Hunt established a fund which was presented to the Institute at a fitting ceremony on May 27, 1920, to establish an annual medal and a sum of money to be awarded under the following rules: 1. The award shall consist of two prizes; first of a gold medal, second of a sum of money; a certificate to accompany each prize. The money prize shall not be awarded to a member over 40 years of age, but under unusual circumstances, both prizes may be allotted to one person provided that he is not over 40 years of age. In general it will be understood that the Committee shall award the money prize to the younger men, rather than the medal. 2. The awards shall be made not oftener than once a year to that person or persons contributing to the Institute the best on al paper or papers on iron and steel. The scope of the term "iron and steel" shall determined by the sub-committee considering the awards. In general, papers dealing with the practical side of the subject have preference over those dealing with the theoretical side in recognition of the fact that Captain Hunt&apos;s main contributions to the industry have been in the improvement of production and quality of material. 3. A sub-committee of three to five, including the Chairman of the Iron and Steel Committee, shall be appointed by the Iron and Steel Committee annually to adjudge the award subject to approval. 4. The awarding committee shall submit its report to the Iron and Steel Committee at its October Meeting, and the award be certified to the Secretary of the Institute in time to permit the presentation to be made at the Annual Meeting of the Institute. 5. The recipient of the award shall be designated "The Hunt Medallist." This prize is administered by the Iron and Steel Committee. J. E. JOHNSON, JR., AWARD This award is made from&apos; the income of a. fund of $3000 donated by Mrs. Margaret Hilles Johnson in memory of her husband, J. E. Johnson, Jr., who was a prominent engineer, author of two valuable volumes on iron blast-furnace construction and practise, vice-chairman of the Institute&apos;s Iron and Steel Committee, and a frequent contributor of papers. to the Institute&apos;s Transactions. This prize is administered by the Iron and Steel Committee. The intent of the donor is to encourage young men in creative work in branches of the metallurgy or manufacture of pig iron with which the professional activities of Mr. Johnson were chiefly concerned. The control of the fund and distribution of the awards having been vested in the Board of Directors of the Institute, this Board has made the following regulations concerning it:

Jan 1, 1925

By P. A. Fisher, J. B. Wilson, D. J. Whitehead, C. J. P. Ball, A. C. Jessup

The properties of a new magnesium alloy ZT1 containing 3.0 pct Th, 2.5 pct Zn, 0.7 pct Zr are described. The alloy possesses good creep and fatigue resistance up to 650°F, is free from microporosity, and is readily sand-cast. ZT1 is shown to be superior to zinc-free Mg-Th-Zr alloys. THE advent of the jet engine created a demand for a light sand-casting alloy capable of being cast into large complex shapes and capable of resisting creep at temperatures up to 500°F. This demand has been largely met by alloys of the magnesium-cerium mischmetal-zirconium types, containing about 3 pct Ce mischmetal and 0.7 pct Zr, typified by Elektron magnesium alloys MCZ and ZREI, the latter alloy also having a zinc addition of 2.5 pct. These alloys utilize the valuable properties at elevated temperatures conferred by the addition of rare earth metals to magnesium, a fact which has been known for many years and discussed by several investigators.1-1 Murphy and Payne8 showed that the addition of the powerful grain-refining element zirconium to Mg-Ce mischmetal alloys produced alloys with attractive room temperature properties combined with good creep properties and castability. With the increasing power of modern jet engines the temperatures to which some of the magnesium parts are subject are likely to exceed the safe working range of the cerium-mischmetal-containing alloys, and at the beginning of the research considerable interest had been shown by aeroplane engine designers in a magnesium sand-casting alloy suitable for service at higher temperatures, e.g., 600°F and above. At an early stage in the development of this type of alloy a check on the fatigue properties at elevated temperatures indicated that, since the fatigue limit even at 108 eversals was appreciably higher than any permissible creep stress, the main emphasis of the research could be concentrated on creep behavior. The primary aim in developing the new alloy has therefore been to attain maximum creep resistance; but due consideration has also been given to other important properties such as castability, tensile strength, and cost. It is by now well established that it is not possible to correlate creep strength with other short time mechanical properties such as are obtained in tensile

Jan 1, 1954

By R. O. Williams

A study utilizing neutron diffraction, electrical resistance, and chemical extraction has been carried out to clarify the chromium-rich part of the miscibility gap previously proposed for this system. This gap appears to be more symmetrical than previously supposed and is very flat. This flatness is believed to be the result of a cooperative phenomenon perhaps of magnetic origin; in particular, it is believed that the chromium-rich phase is antiferromagnetic. The presence of antiferromagnetism is believed to result in an additional strengthening mechanism very sinzilar to that for ordered precipitates. Likewise, it is proposed that the quenched alloys which are known to be ferromagnetic have antiferromagnetic regions which accounts for the maximum in hardness around 75 pct Cr. It is also believed that the existence of antiferromagnetism in other alloys of transition elements might explain some of their anomolous characteristics. THE iron-chromium phase diagram at low temper atures has recently been constructed as shown in Fig. 1(a)1 based upon that work and the work of Fisher, et al2 This system exhibits a number of extraordinary features but perhaps the most striking is the odd shape of the miscibility gap (in the

Jan 1, 1959

The failure of finely-divided sulfide particles to respond to flotation has resulted in a significant loss of our natural resources. As mentioned by Professor Arbiter, the overall recovery of copper from porphyry copper ores is generally between 80 and 85 percent. The recovery of copper sulfides from these ores is about 90 percent, the difference in these recoveries being due to failure of oxide copper minerals to respond to flotation. The 10-percent loss of sulfide copper has not been studied. Losses are known to be in the fractions finer than 74 microns, but the sizes that are not responding to flotation have not been established. In the case of molybdenite, however, it is known that particles finer than about five microns are not recovered. Work in other systems, notably the hematite-quartz system, has shown that good flotation of very fine particles from natural ores is possible (1, 2). The size distribution of one ore that was researched is given in Table 1, and as shown, approximately 50 percent of the ore was finer than 10 microns. Flotation experiments were conducted with this ore, which contained 45 percent iron, utilizing octyl hydroxamate as collector and without any desliming (1). The results of these experiments are presented in Table 2. From the standpoint of mechanisms of collector adsorption, similarities exist between those occurring in the hydroxamate-hematite system and many xanthate-sulfide systems. .This is, multilayers of ferric hydroxamate are present on hematite under flotation conditions (1,3).

Jan 1, 1979

By Pradeep K. Rohatgi, David N. French, Surendar M. Jain, Clyde M. Adams

The effect of solute concentration and diffussivity on dendritic solidification of dilute binary aqueous solutions has been investigated; chlorides of sodium, potassium, lithiurn, and hydrogen were used as solutes. Dendrite spacings were measured in spherical droplets and in unidirectionally solidified specimens. In the droplets, the freezing rate is uniform over the entire specimen and remains constant from the beginning to the end of solidification. In the unidirec-tionally frozen specimens the freezing rate varies within a given volume of liquid during the solidification cycle; in addition, it varies with location uithin the specimen. Mass transport analysis has been used to calculate the supersaturation, AC, supercooling, AT, and transcerse growth velocity, V , of ice dendrites during solidijication from the dendrite spacings measured in the droplels. The ice dendrite spacing in a given solute increases lineary with the solule concentralion at a fixed freezing rate. The ualues of AC, AT, and V increase with an increase in solule concentration. The value of AT in the aqueous solution is of the same order of magnitude as in Al-Cu alloys of the same concentration; the dendrite spacings in Al-Cu alloys also increase with an increase in solute concentralion. For the jamily of aqueozrs solulions incestigaled, the dendrite spacing increases linearly with solute diffusivity at fixed values of concertralion and freezing ,rate. The values of ?C and ?T decrease, whereas the value of V increases with an increase in solule diffusicity. The measured dendrite spacings , L, can be expressed by the relatiun: L = K;(dfa/db) 4 K2C +K3D - K4 where dfs/d? is-change in fraction solid with time (freezing rate), C is solute concentration, D is solute diffusivit K1 = (14 * 4)pmin1&apos;2, K2 = (70 ± 10) pl (moles)- K3 = (24 r 3) . l05 psec (cm)-~. K. = -132 ± 10) 1. FREEZING of solutions is almost always an ehunmix-ing" process because the composition of crystallizing solid generally differs from that of the parent liquid. " Solute concentration and transport are therefore in]portant considerations in solidification of solutions. The influence of these factors on the dendritic solutions produced from metallic solutions is of practical significance since the properties of the solid aggre-gate are often strongly influenced by dendrite spacing.&apos;&apos;&apos; Alexander and Fthines3 found that dendrite spac- ings generally increase with solute concentration in several metallic systems. Michael and Bever1 have observed an increase in a aluminum dendrite spacings in dilute A1-Cu alloys. Rohatgi and AdamsJ have reported a linear increase in a aluminum dendrite spacings with increasing copper contents up to 28 pct in A1-Cu alloys. Bolling and Tiller"&apos; have theoretically examined the effects of solute concentration and diffusivity on the growth of cells and dendrites. Their analysis of dendritic growth assumes a steady-state growth and the maximum possible velocity for dendrite propagation. In addition, the quantitative analysis is restricted to dendrites of rotational symmetry and is therefore not directly applicable to the plate-shaped dendrites of ice obtained in the present study. There are practically no experimental observations of the effect of solute diffusivity on dendrite spacings in metallic systems. The reason appears to be the lack of experimental data on solute diffusion coefficients in liquid metallic solutions. The present work is concerned with the effect of solute concentration and diffusivity on dendritic solidification of dilute aqueous solutions: the solutes examined are potassium chloride. sodium chloride, lithium chloride. and hydrogen chloride. There were several reasons for selecting these solutes. The variation of dendrite spacing with freezing rate in these solutiolls is similar to that observed in A1-Cu alloys.8 These aqueous solutions have almost identical phase diagrams at dilute concentrations. Fig. 1. and the diffusion coefficients show very little variation with solute Concentration.9,10 Dendrite spacings were measured as a function of freezing rate. solute concentration. and solute diffusivity. Dendrite spacings were measured in two different types of freezing systems. droplet and unidirectional, respectively. In the droplet freezing system

Jan 1, 1970

By J. A. SINGMASTERN

THE New Jersey Zinc Co.&apos;s vertical retort plants are believed to have been in continuous operation through the whole year. At Palmerton metal purer than that made from the same ore in the old plant has been produced and has been able to compete successfully with very pure electrolytic metal in die castings and other special uses where extreme purity is worth money. A new plant using this process was put in production by the Grasselli Chemical Co. at Meadowbrook, W. Va., early in the summer. It is said to be working very satisfactorily. It is understood that this plant will not produce high-grade metal. Two patents issued to Bunce and Mahler (Nos. 1,749,126 and 1,749,127) describe a method of operating the vertical retort so that practically lead-free metal can be obtained from ores containing consider- able lead. The zinc vapors and other gases leaving the reaction zone are filtered through a column of material maintained at a temperature high enough to prevent much zinc from condensing. The filtering medium is either periodically or continuously changed.

Jan 1, 1931

By Elton A. Youngberg

J. H. HEARDING, Jr.*—Extremely hard ferruginous chert (taconite) was encountered in driving a drift at the Fraser underground mine near Chisholm, Minn., on the Mesabi Iron Range. In order to get better results in drilling in this ground, it was decided to try tungsten carbide bits. In the beginning, 1½ in. tungsten carbide bits and 1 1/8 in. round-lugged alloy steel drill rods with "jack-stud" inserts were used. Considerable difficulty was encountered because the jack-stud became loose in the drill rods. Because there was not enough alloy steel drill rod on hand, we began to insert jack-studs in the ordinary high carbon drill rods and found, to our surprise, that there was less trouble with jack-studs working loose in these rods than there had been with the alloy steel rods. As a result, use of the alloy steel rods has been discontinued entirely. Under the heading "Drilling Procedures" the statement is made that all holes are started with detachable bits or conventional steel to prevent undue strain on the tungsten carbide bit inserts when collaring a hole on uneven ground. This practice was followed in our work originally for the same reason. It was soon found, however, that the holes could be started with the tungsten carbide without injuring the inserts if the drill operator was careful and did not give the drill too much air until the bit had a chance to seat itself in the rock. J. C. FRANZ*—In a discussion of other technical papers with reference to percussion drills and the use of carbide tungsten bits, it was my impression that the authors reported one of the first difficulties experienced with the use of standard, conventional percussion drills, was insert bit failures due to crushing of the bit inserts when the bits became dull. During the past few years, some of the rock drill manufacturers, I am told, have adopted an air drill for use with the carbide bits that have a lighter blow and faster rotation than the regular machine. This machine has been tested and the carbide bit failures have been considerably reduced. L. W. DUPUY†—The difficulties Mr. Youngberg mentions that were had with rod and coupling breakage call to mind similar troubles experienced at the Picacho mine in California near Yuma.6 The commercial couplings then available were found to be tempered almost to brittleness. Rod breakage was usually in the threads near the end of the rod. The highly-tempered couplings would break as soon as the rod broke. The solution was to thoroughly anneal the couplings and to put in only a very mild temper. Subsequently the alloy used in making the couplings was changed from the original by the manufacturer, but still only a very mild temper was used. The result was that the softer coupling would give but would not snap and release its hold on the broken rod thread. Fishing jobs were reduced to the few where the rods broke at the rod end of the thread. Thread breakage on the rods was further reduced by thorough annealing prior to tempering. The data Mr. Youngberg presents regarding the use of carbide inserts on long blasthole drilling is most interesting and it would appear that the use in this manner of percussion drills and carbide bits will have many applications. W. M. WOODWARD*—How many feet of hole, on the average, do you get from a tungsten carbide bit, and is there much variation from this average? E. A. YOUNGBERG (author&apos;s reply) —In recent months the 2 in. tungsten carbide bit footages in long hole drilling hake varied from 115 .to 140 ft monthly. The footages obtained from individual bits vary from several feet to over 300 ft, however the life of a majority of the bits will be within 25 ft of the average.

Jan 1, 1950

By Arthur C. Simmons

The area producing Pennsylvania-grade crude oil declined sharply in 1943, with a daily average production in the entire area of 71,056 bbl. as against a daily average in 1942 of 77,786. The total decline in the Pennsylvania-grade area amounted to 2,456,311 bbl., and 1,g81,z71 bbl. of this occurrcd within the state of Pennsylvania. The principal decline occurred in the Bradford field, where it was caused primarily by a drastic reduction in well completions. All of the zones in the Pennsylvania-grade producing area showed a decline except the part of Ohio that produces that grade, where production increased very slightly over 1942. Table I shows the average daily production by months for the several districts of the area. Table z is a comparison of the production in the two districts within the state of Pennsylvania. It is interesting to note that the Bradford field produced approximately half the total quantity of Pennsylvania grade but accounted for nearly three-fourths of the decline in production from the previous year. It is believed that this decline is ocasioned by restrictive price ceilings and a lack of adequate manpower to drill the necessary wells to maintain production. Stocks of Pennsylvania Grade At the beginning of 1942, stocks of Pennsylvania-grade crude totaled 3,196,000 bbl. and at the beginning of 1943 they totaled 2,626,000 bbl. At the end of 1943 the stocks of Pennsylvania-grade crude had declined to 1,95z,000 bbl. The available crude stocks have been almost completely consumed, as nearly all of the present crude stocks are "unavailable" and required for

Jan 1, 1944

By Arthur C. Simmons

The area producing Pennsylvania-grade crude oil declined sharply in 1943, with a daily average production in the entire area of 71,056 bbl. as against a daily average in 1942 of 77,786. The total decline in the Pennsylvania-grade area amounted to 2,456,311 bbl., and 1,g81,z71 bbl. of this occurrcd within the state of Pennsylvania. The principal decline occurred in the Bradford field, where it was caused primarily by a drastic reduction in well completions. All of the zones in the Pennsylvania-grade producing area showed a decline except the part of Ohio that produces that grade, where production increased very slightly over 1942. Table I shows the average daily production by months for the several districts of the area. Table z is a comparison of the production in the two districts within the state of Pennsylvania. It is interesting to note that the Bradford field produced approximately half the total quantity of Pennsylvania grade but accounted for nearly three-fourths of the decline in production from the previous year. It is believed that this decline is ocasioned by restrictive price ceilings and a lack of adequate manpower to drill the necessary wells to maintain production. Stocks of Pennsylvania Grade At the beginning of 1942, stocks of Pennsylvania-grade crude totaled 3,196,000 bbl. and at the beginning of 1943 they totaled 2,626,000 bbl. At the end of 1943 the stocks of Pennsylvania-grade crude had declined to 1,95z,000 bbl. The available crude stocks have been almost completely consumed, as nearly all of the present crude stocks are "unavailable" and required for

Jan 1, 1944

By N. J. Grant, F. B. Cuff

DURING a recent investigation of high-purity aluminum,&apos; evidence was found for grain-boundary sliding and migration at room temperature. The investigation was concerned primarily with an electron-microscopic study of a fine (approximately 1 micron) network that appeared on the surface of chemically polished aluminum. The nature of the network will not be discussed since it serves only as markers showing relative displacements in this instance. The pertinent observation, shown in Fig. 1, was made on a flat tensile specimen which had been strained about 8 pct at room temperature. As can be seen in this electron micrograph, a grain boundary has undergone a certain amount of sliding. The reason for the existence of the two differently appearing networks is given in the foregoing reference. For present purposes, however, the transition region can be disregarded. A close study of this picture reveals that in addi- tion to sliding there is a narrow band adjacent to and above the grain boundary. Fig. 2 is a schematic drawing showing the essential features of this band.

Jan 1, 1959

By J. W. Taylor, E. G. Zukas

THE results of shock-loading studies on copper were reported several years ago by smith. In his experiments, Smith found that there was a correlation between the shock direction and the orientation of twins which the shock produced. By using free-surface-type shots in which the free surface of the specimen was not normal to the shock direction, he showed conclusively that twinning of copper in impulsive loading was caused by the rarefaction wave. Similar tests with iron, however, showed that it twinned during compression. More recent studies of iron2 and on Fe-Si single crystals3 have shown that twinning can be suppressed in these materials by shock loading at pressures high enough so that the velocity of the shock wave exceeds the elastic-wave velocity. From these observations, it appeared that twinning was caused by the shear stresses present in the zone undergoing adjustment from one-dimensional to three-dimensional loading. At high pressures, such a zone becomes so thin that there is insufficient time for the relatively ordered motion of atoms involved in twinning to occur. Twinning in copper, therefore, cannot be produced by a single compressive shock wave because resolved shear stress large enough to create twins exists only for a very short time (0.01 psec or less) before the pressure increases suddenly and loading becomes essentially hydrostatic. (A typical pressure vs time record for a copper shot, illustrating the short rise time of the compression wave, is shown in Fig. 1.) If, on the other hand, a second shock wave can be created in a precompressed sample, then the new elastic limit is several kilobars,4 and a resolved shear stress sufficient to cause twinning should be maintained for an adequate time period (0.1 psec or more). This experimental situation can, in fact, be realized. The experimental arrangement used to do so is shown in Fig. 2. By utilizing the pressure transformation in Fe-V alloys, it was possible to shock-load the copper in compression while the copper was already precompressed. In the first test, an 8 wt pct V-Fe sample was used as a driver for loading the copper, and the copper was exposed to the following series of compressive shocks: 1) an elastic wave of about 8 kbars, which is usually ignored in shock studies; 2) the pressure transformation wave for the driver of 200 kbars; and 3) the driving shock wave of 270 kbars pressure. Metallurgical determination of the angular twin distribution, shown in Fig. 3, with respect to the shock direction and the shock rarefaction direction (which was 23 deg from the shock direction) showed that twinning took place

Jan 1, 1965