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By A. H. Geisler, R. F. Mehl, C. S. Barrett

The mechanism by which the supersaturated solid solution of 20 per cent silver in aluminum decomposes has been reported in two previous publications.1'2 The analysis of streaks in Laue photograms showed that thin platelike particles (the so-called Guinier-Preston aggregates) form upon matrix planes in the early state of decomposition.1 The size of these particles is larger, the higher the temperature at which they form in accordance with nucleation theory;³ at all temperatures they increase in size with aging.2 When they have grown thick enough to afford three-dimensional diffraction, powder X-ray photograms show that the structure is not that of the equilibrium precipitate but that of a transition lattice . Sincc this is also platelike in shape and also lies upon the (III) matrix planes with the [IIO] direction in the matrix parallel to the [II.O] direction in it seems likely that the original platelet particles are merely in an early stage of formation, and thus finely dispersed. The atomic spacing and pattern on the (00.1) plane in y' are identical with those on the (111) matrix plane to which it lies parallel, and since comparable directions in the two planes are parallel, the lattices are thus coherent at the interface; an analogous coherence has been found in aluminum-copper alloys.3 The structures y' and y are both close-packed hexagonal and are oriented alike; they differ only in interatomic distances. Consequently, y' is regarded as y strained from its ordinary dimensions by the lattice coherency between it and the matrix.2 The lattice movements that transform the matrix to the equilibrium precipitate appear to be very simple.2 The mechanism of precipitation in this system is simpler and is more precisely known than that in any other system hence the system should be a profitable one for the difficult task of correlating property changes with structural alterations. The present report provides additional studies on powder X-ray diffraction from alloys of 10 per cent, 20 per cent and 30 per cent Ag, and presents the correlation of crystallographic changes with changes in microstructurc, Brinell hardness and electrical resistivity of the three alloys. Preparation of Samples and Experimental Procedure The preparation of the 20.2 per cent Ag alloy has been described2 Alloys containing 9.9 and 29.7 per cent Ag were prepared from 99.97 per cent A1 and 99.99+ per cent Ag using a similar procedure. Rolled

Jan 1, 1943

By R. F. Mehl, C. S. Barrett, A. H. Geisler

The mechanism by which the supersaturated solid solution of 20 per cent silver in aluminum decomposes has been reported in two previous publications.1'2 The analysis of streaks in Laue photograms showed that thin platelike particles (the so-called Guinier-Preston aggregates) form upon matrix planes in the early state of decomposition.1 The size of these particles is larger, the higher the temperature at which they form in accordance with nucleation theory;³ at all temperatures they increase in size with aging.2 When they have grown thick enough to afford three-dimensional diffraction, powder X-ray photograms show that the structure is not that of the equilibrium precipitate but that of a transition lattice . Sincc this is also platelike in shape and also lies upon the (III) matrix planes with the [IIO] direction in the matrix parallel to the [II.O] direction in it seems likely that the original platelet particles are merely in an early stage of formation, and thus finely dispersed. The atomic spacing and pattern on the (00.1) plane in y' are identical with those on the (111) matrix plane to which it lies parallel, and since comparable directions in the two planes are parallel, the lattices are thus coherent at the interface; an analogous coherence has been found in aluminum-copper alloys.3 The structures y' and y are both close-packed hexagonal and are oriented alike; they differ only in interatomic distances. Consequently, y' is regarded as y strained from its ordinary dimensions by the lattice coherency between it and the matrix.2 The lattice movements that transform the matrix to the equilibrium precipitate appear to be very simple.2 The mechanism of precipitation in this system is simpler and is more precisely known than that in any other system hence the system should be a profitable one for the difficult task of correlating property changes with structural alterations. The present report provides additional studies on powder X-ray diffraction from alloys of 10 per cent, 20 per cent and 30 per cent Ag, and presents the correlation of crystallographic changes with changes in microstructurc, Brinell hardness and electrical resistivity of the three alloys. Preparation of Samples and Experimental Procedure The preparation of the 20.2 per cent Ag alloy has been described2 Alloys containing 9.9 and 29.7 per cent Ag were prepared from 99.97 per cent A1 and 99.99+ per cent Ag using a similar procedure. Rolled

Jan 1, 1943

By E. P. Abrahamson

The effect of transition element binary solid solution additions upon the re crystallization temperature of nickel has been investigated. All additions raised the re crystallization temperature. Both the rate of change of re crystallization temperature with at. pet solute and the limit of initial linearity are found to correlate with the free atom ground state outer electron configuration of the solute element. A comparison of all of the correlations for the transition elements studied has yielded a set of empirical relations, which allows the prediction of the effect of dilute binary transition elements on the recrystallization temperature of other transition elements. The work of Abrahamson, et al.1-7 on dilute binary solution alloys indicated a correlation between the free atom ground state electron configuration of the solute and both the brittle-ductile transition and re-crystallization temperature. Further, it has been shown3,4 that the limit of initial linearity may also be correlated with the solute electron configuration. Since previous studies have dealt with bee and hexagonal base elements, this study is made to note what effect, if any, the fee base structure might have. Nickel also serves to give a solvent configuration which will allow the comparison of all of the transition element solvents. Olsen8 has studied the effect of some trace elements upon the recrystallization of nickel. He included only Ti, Zr, W, Mn, and Co of the transition elements. The differences in change of recrystallization temperature were attributed to the solute atom size and to the solubility of the solute in nickel. PROCEDURE All alloys were made using 99.9 + pet Ni with 0.003 C, 0.015 Fe, 0.007 0, and 0.0007 H. The solute elements were 99.9 + pet pure. According to the published binary phase diagrams9 and metallo-graphic examinations at X750, all solute elements were in solid solution. The alloys were arc melted and remelted four times in the form of cubic 200-g buttons under an argon atmosphere. They were then hot forged at 800oC to 0.750 in. diam, machined to 0.60 in., vacuum annealed for 1 hr at 700°c, swaged to 0.40 in. and annealed at 700oC for 1 hr in vacuum. The grain size was checked and found to be 77 * 20 grains per sq mm. The specimens were then swaged to 0.187 in., yielding 76 ± 1 pet cold work. All alloys were then chemically analyzed for the solute addition. The interstitial contents remained at the values of the starting material when checked on random alloy specimens. The swaged rod was cut into 8.25 in. lengths and heat treated in a gradient furnace for 1 hr. The gradient was maintained at 250" to 850°C over an eight inch length, recorded by twelve thermocouples. Control was ± 3oC, accomplished at the hot end. The recrystallization was determined metallo-graphically over the entire specimen. The criterion chosen was that point on the specimen showing the first recrystallized grain at a constant magnification, X200. Specimens were repeated, and the agreement was found to be generally ± 3oC.

Jan 1, 1962

By C. E. Gregor

Current modern trends in mining show that hoisting shafts are being expected to fulfill an important ventilation function. However, where rigid guides and supporting structures are mandatory, ventilating power costs will be high, unless the transverse structures (shaft sets) are streamlined. In the complex configurations of hoisting shaft furniture patterns, either for original design purposes, or for the adjustment of an existing shaft, a useful degree of aerodynamic optimization, by reduction of overall resistance, can only be effectively evaluated by model studies in a special purpose wind tunnel, as described herein. The author has shown that, in one particular case, an annual power cost saving of more than $50,000 was indicated, mainly by the selection of buntons and dividers of improved aerodynamic profile. Mining companies are now realizing the advantages that can accrue through proper attention to the aerodynamic aspects of mine shaft design. With progressive demands of civilization for an ever greater supply of coal and metals, and with greater depths of working, higher rates of extraction, advanced degrees of mechanization, and improved standards of environmental health and work comfort, shaft design is becoming an extremely important aspect of mining operations. In addition, because the cost of sinking, equipping, maintaining, and operating a mine shaft is continually increasing, there is a greater incentive to use a shaft for the maximum duty, consistent with economy. The current natural tendency is therefore to sink multi-purpose shafts, to install as much equipment as is safely and effectively possible to operate; and then, over and above all these functions, to use the shaft to its maximum possible ventilating capacity, as a major, or auxiliary, airway. Clearly, this latter additional function can only be employed at a significant cost, since the most economic operating airways are smooth-lined and devoid of internal rigid furniture. It is true that hoisting functions can be carried out in such shafts if rope guides are used, but only under restricted conditions. Where a manway must be provided, fixed guides and supporting structures are mandatory, and ventilation costs become accentuated. It is generally recognized that the prime element of cost in ventilating a mine can be represented by the power required to drive the fan unit. It is also known that the largest component of total mine resistance is that of the downcast shaft, where this shaft is equipped with rigid guides for hoisting purposes. The pressure loss varies directly as the resistance of the shaft, in accordance with a modification of the Atkinson equation p = RQ2/3600. Furthermore, the air horsepower drawn is given by the equation AHP = (p x 0/33000. Therefore, the power required to drive the fan unit varies as the resistance of the shaft and the cube of the air quantity. Clearly, if Q is a specified minimum, then the only way to minimize the pressure loss (and the power costs) is to reduce the shaft resistance R. (See Table I for a list of symbols.) The resistance to airflow of a shaft equipped with rigid guides and supporting structural sets consists of two components which, for the sake of analytical simplicity, can be regarded as additive. 1) Frictional resistance, represented by the viscous frictional forces within the boundary layer, as air flows along the surfaces of the walls and the periphery of the vertical elements (guides, pipes, cables, ropes, etc.) of the furniture. The friction loss can be readily calculated by the Atkinson equation, after selection of a suitable value for the friction factor K from the McElroy compilation.' KxLxO xQ2 5.2 xA3 Friction loss can be minimized by lining the shaft walls (particularly if of circular or elliptical cross-section) with a smooth continuous lining of monolithic concrete.

Jan 1, 1968

Bernard MacDonald, Guanajuato, Mexico (communication to the Secretary*):—Mr. Iceyes's paper is very interesting to me because of my personal experience with the development of the ore-deposits of Lake Valley.

Jan 1, 1909

By J. C. Scully, G. Sanderson

The electrolytic formation of y hydride in thin foils of Ti-5Al-Z.5Sn alloy and four Ti-A1 binary alloys has been studied by electron microscopy and electron diffraction. Two orientation relationships have been found: THE adsorption of hydrogen by titanium alloys from aqueous solutions has been widely reported. This can occur, for example, in both alkaline' and acidic2 pickling baths, in chemical polishing374 and electro-polishing Solutions,3,4 during cathodic polarization5" and under certain corrosion conditions,7,8 Etching reagents may also produce visible precipitates, sometimes after an aging period.9 During an investigation into the stress corrosion susceptibility of a titanium alloys by thin foil electron microscopy many observations have been made of hydride precipitation which has been deliberately promoted by techniques that are described below. The characteristics of hydride precipitation are reported and the observed crystallographic orientation relationships are discussed with reference to distortion in the titanium lattice created by the presence of the hydride. EXPERIMENTAL TECHNIQUE One grade of commercial titanium and five alloys were examined. Their composition and hardness values are shown in Table I. All the materials were in the form of thin sheet, 0.05 to 0.065 cm thick, which had been annealed after cold rolling. Foils suitable for transmission electron microscopy were made in two ways: a) by chemical polishing; and b) by elec-tropolishing. The solution used for chemical polishing was a mixture of 44 pct HF and 73 pct HNO3 in the volumetric ratio 2:3. During this polishing specimens were manually moved up and down in the solution. The reaction was veFy rapid, specimens thinning to foil thickness (2000A) in 5 min. Since chemical polishing solutions tend not to cause hydride contamination if they are kept cool3 no attempt was made to prevent the solution from becoming hot during the thinning operation. Electropolishing was performed at -30° C with a mixture3 composed of 295 cu cm methyl alcohol, 175 cu cm n-butyl alcohol, and 30 cu cm perchloric acid with an applied voltage of 40 v after chemically thinning specimens to approximately 0.017 cm thickness in a cool solution of 44 pct HF, 40 vol H2O2, and water in the volumetric ratio 1:6:3. EXPERIMENTAL RESULTS 1) Ti-5A1-2.5Sn Alloy. The Ti-5A1-2.5Sn alloy was severely contaminated by hydrogen during the chemical polishing. Foils obtained in this way contained large amounts of the y hydride phase. A typical micrograph is shown in Fig. l. The laths were identified as the hydride phase by selected-area diffraction of a large number of foils examined in a tilting stage that could be turned through 40 deg. Using the lattice spac-ings of the alloy obtained by X-ray diffraction as a standard the a value of the hydride was determined fromo the electron diffraction patterns to be 4.38 to 4.40A. The accuracy of this figure is only about ±2 pct. Further evidence of the identification was obtained by vacuum annealing chemically polished foils of the alloy at 500°C. This resulted in the dissociation of the hydride with the production of dislocations and possibly vacancy loops as shown in Fig. 2. The hydride

Jan 1, 1968

By R. H. Richards, A. E. Woodward

In Rittinger's Aufbereitungskunde of 1867 occurs (p. 195) the following table, which shows the rate of falling in water of fragments of minerals, of irregular shapes and of five different specific gravities: Diameter of particles in millimeters. 10 8 6 4 3 2 1 .5 Sp. Or. Velocity in meters per second. Auriferous silver, 16..9 .8 .7 .57 .5 .4 .29 .20 Galena,. ..7.5 .62 .55 .48 .39 54 .28 .20 .14 Pyrites,. ..5.0 .49 .43 .38 .30 .26 .22 .15 .10 Quartz,. ..2.6 -30 .27 24 .19 .17 .14 .10 .07 Coal,. ..1.3 .13 .12 .10 .08 .07 .06 .04 .03 With the purpose of extending this valuable table, to cover a larger number of minerals and sizes of each mineral, and of making it more easy of application in deciding upon a sieve-scale for any group of minerals, we have prepared the curves of velocity of fall of bodies in water shown in Plates I., XI., 111. and IV., using Rittinger's formula V= 2.44d(8 —1) where V= velocity in millimeters per second. " D = diameter of particles in meters. " 8 = specific gravity of the mineral. These curves embrace a large number of specific gravities, and for each specific gravity the relation of the diameter of the mineral particle to the velocity of its fall in water is given for all diameters and velocities used in practice. The second diagram is an enlargement of the lower left-hand corner of the first, the third bears the same relation to the second, and in like manner the fourth to the third. Plate I, therefore, covers the work of the coarsest jigging 2 inches in diameter; and under

Jan 1, 1890

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 John J. Stokes

Literature on the electrolysis of aluminum from cryolite melts and on the structure of these .melts is surveyed critically. Data on density, freezing point, and other properties are reviewed. Theories of the electrolysis are examined in the light of these data. Two theories are presented which account equally well for the observations. In the early days, the process was thought of as a simple one. The actual mechanisms must be tremendously more complex. This paper is devoted to a rather narrow part of the whole subject, namely, what ions are present in the bath, and by what mechanism the current is carried. Using cryoscopic data, Rolin has determined the following composition for molten cryolite. Na2,AlF 3Na + 3F + AlF [1] He postulates the following equation for the ioniza-tion of alumina at low concentrations Al2O3 Al + AlO2 +O. [2] At concentrations above 0.025M he supposes the ionization of alumina to proceed as follows Al2O3 AlO + AlO2. [3] Rolin's mechanism of electrolysis for the more concentrated solution in Eq. 3 is as follows. The AlO' ion migrates to the cathode. where it is dis- charged, giving metallic aluminum and 0' ions which migrate to the anode. The AlO2- ion migrates to the anode, where it is discharged, giving Al ions and oxygen which reacts with carbon to form CO2 In the case of the extremely dilute solution in Eq. 2 the Al ion migrates to the cathode and the AlO2-and 0 migrate to the anode as before. Another possible mechanism for the electrolysis follows. Ionization of Cryolite Na3AlF4 = 2Na + 2F + NaAlF, Na + AlF-AlF+Na + F [4] Addition of Alumina 2Na2AlF+ 2AL2O4 6Na + 3A12O3F4 [5a] Al2O2F 2AlOF2 [5b] Cathode Process AlF, + 3e+ 4F + Al. [6] Anode Process AlOF2 + 2F AlF1 + 1/20, + 2e or A12O2F + 4F-2A1F; + 0, + 4e. [7] Although both Rolin's and the present mechanism of the Hall process may be qualitatively satisfactory, present data are not adequate for quantitative tests of the theories.

Jan 1, 1959

By R. F. Ashton, D. S. Thompson

In reporting results of precipitation hardening experiments, it is customary to include such conditions as solution heat-treatment temperature, specimen size, and quench medium as well as the aging time and temperature. One portion of thermal history that is often overlooked is the effect of the heating rate employed to achieve the aging temperature. It is the intent of this note to demonstrate the importance of the rate of heating to aging temperatures. This work was carried out on the aluminum alloy 7075 aged at 162oC, a temperature commonly used to obtain stress corrosion resistant tempers. A 2 in. thick plate of 7075 was quenched into 24°C water after solution heat-treatment for 2 hr at 470°C. Approximately 13 in. around the periphery of the plate was discarded to minimize quench rate variations, and the remainder was divided into 0.5 by 1.8 by 2.0 in. blocks which were held at room temperature, 24oC, for 4 days. This aging, or incubation period, at room temperature allowed a copious supply of GP-zones to form. Blocks were then heated at various rates to 162oC using the practices shown in Table I. Both single- and two-step aging practices were employed for each heating rate. The single step consisted of heating directly to temperature at the indicated rate while the two-stage practice included an interruption of heating for 7 hr at 107°C. In the case of the two-stage 100°C per min heating rate experiment, the specimens were returned to room temperature after 7 hr at 107°C where they were held for 16 hr be-fore finally heating at this rate to 162°C. This devia-tion in practice is not considered to be significant. Blocks were removed after various times at 162oC, and aging curves were determined from duplicate R. F. ASHTON and D. S. THOMPSON,Member AIME, are Senior Scientists, Metallurgical Research Division, Reynolds Metals Company, Richmond. Va. Manuscript submitted December 2. 1968. IMD Table I. Aging Practices Two-step Single-Step Heating Rate* Aging Aging Heating Method oC per Min A B Programmed Air Oven 0.23 * 0.01 C D Programmed Air Oven 0.93 ? 0.03 E F Air Oven at Temp -10 G H Oil Bath at Temp ˜100 *Heating rate was measured with a thermocouple at the center of a specimen. An average value between the starting temperature and 3°C below the aging temperature is reported for practices E-H. PRACTICES 70 — A B C E and G 50 - 2 4 6 810 20 40 60 HRS.AT 162°C Fig. 1—The influence of processing variables on 7075 aging curves. Fig. 2—7075 aged according to practice H (single-step aged, fast heating rate) for 3 hr. Magnification 100,000 times.

Jan 1, 1970

By Sidney Snook

FLUORSPAR production is the most important industry in a compact area in southern Illinois and western Kentucky bordering the Ohio River. Producers' activities do not usually figure much in the mining news of the country, so that few know that the last year or so has been an unusually active one. Mine shipments more than doubled in 1939 compared with the poor year 1938. The average price changed but little, though it is now about one-sixth higher than at the beginning of last year. The outbreak of war in Europe a year ago lent an immediate stimulus to the industry, though only about 15 per cent of the domestic consumption is normally imported, thanks to a tariff of $8.40 per ton, equivalent to about 30 per cent ad valorem. Be- cause of the increased production and many expansions and improvements in the mines and plants, the period since the beginning of 1939 has been the most important one for the industry in the last 15 years.

Jan 1, 1940

By J. C. Williams, M. J. Blackburn

Several of the decomposition processes that can occur in supersaturated phases in a Ti:11.6 wt pct Mo and a Ti:20 wt pct V alloy have been studied by transmission electron microscopy. The deformation induced "marternsitic phase" in the Ti:Mo alloy has been found to have a bcc or bct structure rather than the previously reported hexagonal structure. The morphology of&apos; the transformed region is a rather complex asserrlblage of twins, twinning occurring in one or more systems; this internal twinning has been found to occur on (112). The w phase is formed in both alloys on aging and is present in the Ti:Mo alloy after quenching. The structure of this phase has been confirmed as hexagonal in both systems, however, differences in morphology and stability are found between the two alloys. Thus in the Ti-Mo alloy the w phase has an ellipsoidal morphology with the major axis lying parallel to <111>ß or [0001]w while in the Ti-V alloy the phase forms as cubes, the cube faces lying parallel to {100}ß or {2021}w Some observations on the particle sizes, volume fraction, and composition of the w phase in the Ti-Mo alloy are listed. The mode of formation of The a phase from the (ß + w) structures is also different in the two alloys. In the Ti-Mo alloy the a phase is formed by either a cellular reaction or by the growth of isolated needles, whereas in the Ti-V alloy the a phase is nucleated at an w:ß interface and grow to consume the w phase. Some of the difjerences in behavior of the w phase are attributed to the mismatch between it and the solute enriched ß matrix in which it forms. MaNY transition elements tend to stabilize the bcc or ß-phase when added to titanium. In general two types of phase diagrams are produced, either a ß-stabilized (ß-isomorphous) system, e.g., Ti:Mo, -Ti:V, Ti:Nb, or a ß-eutectoid system, e.g., Ti:Cr, Ti:Fe, Ti:Mn. In previous papers&apos;-4 the phase transformations in the a-phase and (a + ß)-phase alloys have been described and this work has been extended to ß-stabilized systems. Specifically, transformations in the alloys Ti:20 wt pct V and Ti:11.6 wt pct Mo have been studied; in both of these alloys the ß phase is retained at room temperature when quenched from the ß-phase field. A number of phase transformations can occur in such metastable ß phases and the two alloys were chosen to include most of the transformations reported for ß-stabilized systems. We list these possible phase transformations below. Ti:11.6 Mo quenched from >780°C to retain the ß phase: a) The w phase can form on quenching.5 b) Martensite can be produced by subzero cooling or deformation. Two martensite habit planes have been reported in Ti:Mo alloys; (334)ß and (344)ß=6 c) On aging at temperatures <-550° C the w phase is formed before the a-phase.5,7 d) On aging at temperatures >550°C the a phase is formed.7 e) The martensite can be tempered. It has been reported that the a phase rather than the ß phase is precipitated during tempering.&apos; Ti:20V quenched from >660°C to retain the ß phase:9 a) At aging temperatures <260°C separation into two bcc phases occurs. b) The w-phase is produced prior to the a phase on aging at temperatures <-400°C. c) At temperatures 2400°C the a phase is formed directly. T-T-T diagrams describing the temperature and time regimes for the formation of these phases have been published7,9 for a Ti:12 pct Mo and a Ti:20 pct V alloy. We have attempted to investigate these transformations using transmission electron microscopy, however thin foils undergo a spontaneous transformation in all conditions except the equilibrium (a + ß) structure. This transformation has been reported previ0usly10,11 and we will comment on its morphology and nature in the various sections of experimental results. EXPERIMENTAL The compositions in wt pct of the two alloys investigated were: Ti:11.6 Mo, 0.100 02, 0.006 N2, 0.0015 H2 Ti:20V, 0.0574 O2, 0.0111 N2, 0.005 H2 These alloys were cold-rolled to 0.020 in. thick sheet. Specimens were heat treated in vacuum or in inert gas at temperatures >500°C and in a circulating air furnace at temperatures <500°C. Thin foils were prepared using standard techniques, described in detail previously." Dark field micrographs were obtained using high resolution technique. RESULTS Martensitic Transformation in Ti:11.6 pct Mo. Detailed study of the deformation induced martensite is not possible due to a spontaneous transformation which occurs near the edge of thin foils as shown in Fig. 1. Similar transformations have been observed in iron-" and copper-base13 alloys as well as other titanium alloys, but some observations specific to the Ti:1l.6 Mo alloy are listed below. a) The boundaries of these transformed regions are glissile and move under the influence of the electron beam during examination. b) Selected area diffraction indicates the transformed regions have the same structure as the matrix, being separated by tilt boundaries. The misori-

Jan 1, 1969

By J. Eldridge, K. L. Komarek

Activities of aluminum in solid Fe-Al alloys have been determined between 0 and 75 at, pct Al and 1100" and 1400°K by an isopiestic method in which iron specimens, heated in a temperature gradient, are equilibrated in a closed all-ceramic system with aluminum vapor. The activity of aluminum in these alloys shows a strong negative deviation from Raoult&apos;s law at low concentrations but increases rapidly above 40 at. pct Al. The enthalpy and entropy of mixing me both negative. For an alloy with equiatomic composition the values are: HM = -7300 cal and SM = -0.85 eu. Sodium chloride has been added at lower temperatures to accelerate the evaporation of aluminum. Equations have been derived to calculate activities of aluminum from experimental data. THE Fe-Al system has been the object of a great number of investigations.&apos; Most of these studies have been concerned with the phase diagram and specifically with the order-disorder reactions in the range of solid solutions of aluminum in iron. The results have been compiled by Hansen2 and presented as a complete phase diagram, Fig. 1. More recently, Taylor and ones&apos; have found that both ordered and disordered alloys can exist in the a field up to the solidus curve separated by a line starting at 18.75 at. pct Al at room temperature up to 37 at. pct Al at 1375°C. Chipman and coworkers4-7 have studied repeatedly the activity of aluminum in liquid dilute Fe-Al alloys. They have measured the distribution equilibrium of aluminum between liquid iron and

Jan 1, 1964

By W. B. Price

AT the New York meeting of the American Institute of Mining and Metallurgical Engineers held in February, 1926, W. H. Bassett and J. C. Bradley presented a paper entitled "Exudations on Copper Castings."&apos; The purpose of the present paper, as the title suggests, is to call attention to somewhat similar phenomena which the authors have encountered in brass and bronze. From a study of the examples given, a more-or-less speculative theory of "inverse segregation" is advanced. Protuberances on Admiralty Brass In the rolling mill of the Scovill Manufacturing Co., there have been found quite commonly bars of certain alloys which had a sort of shaggy roughness on the surface due to slight metallic protuberances. No special attention was paid to these until some bars were found on which these protuberances were heavy enough at the bottom of the bars to produce a blistered appearance. A sample of the protuberances was milled off the surface of the bar illustrated (Fig. la) and upon analysis was found to contain 66.66 per cent. copper, 4.02 per cent. tin and 0.03 per cent. lead, whereas the average composition of the bar was 70.21 per cent. copper, 1.21 per cent. tin, and 0.01 per cent. lead. A sample of the shaggy-rough protuberances at the very top of a bar was also analyzed and was found to contain 2.45 per cent. tin, indicating that it was probably of the same origin as the blistered areas. These results were not entirely unexpected for previous analyses of this alloy had revealed that the surface was richer in tin than the rest of the bar. This, of course, is contrary to what we would expect from a consideration of the equilibrium diagram and has been called "inverse segregation." Fig. 16 is a cross-section of a bar through the protuberances on the surface. It reveals that there is a decidedly different structure through the raised areas and seems to indicate that the bar originally solidified

Jan 1, 1927

By Finney, W. R.

MUCH has been said and written of the "Big Inch," of the terrific obstacles encountered in its construction, of the colorful and tough men engaged in its building, but little has been publicized of the engineering and economic problems behind the scenes. Long before Pearl Harbor it was apparent to the petroleum industry that a critical oil shortage could be expected along the Atlantic seaboard, owing to delay in tanker deliveries as a result of convoy movements, and to allocation of vessels for foreign shipments. This area, with a normal consumption of approximately 1,800,000 barrels per day of oil and products, was almost entirely supplied by tanker. Pipe lines supplied an average of only 20,000 barrels per day in 1939, 40,300 barrels per day in 1940, and 55,000 barrels per day in 1941. A small amount of oil and products was also delivered via barge.

Jan 1, 1943

By Michel Elle, John Chipman

The equilibrium of gaseous H20-H2 mixtures with liquid iron-columbium alloys in the range 0.2 to 2.4 pct Cb shows that the activity coefficient of oxygen is strongly diminished by Cb. The oxide in equilibvium with the melt is identified as CbO2. The equi-librium constant at 1600 deg C is [%Cb][fo. % 0]2 = 2.9 x 10-4 where log fo= —0.14 [%Cb]. The deoxidizing power is comparable to that of vanadium, COLUMBIUM (niobium) is finding increasing use as an alloying element in steel. It forms several stable oxides and is removed from the steel bath by oxidizing slags. The specific oxide formed in steel-making is not known although Sazanov snd Shvarts-man,&apos; in their study of its partition between slag and metal, have assumed this to be Cb2O5 It is the purpose of this study to determine its deoxidation equilibrium at 1600°c, the nature of the oxide formed and the interaction between columbium and oxygen in the melt. The investigation was based on the reaction H2 + O=H2O; Kl=ph2o/(pH2[%O]) [1] in which 0 signifies oxygen dissolved in the liquid Fe-Cb alloy. The method and equipment of recent studies2,3 were utilized. In brief, the molten alloy, contained in a small crucible, is held in a controlled mixture of steam, hydrogen, and argon until equilibrium is reached. It is then cooled quickly in a stream of helium and analyzed for columbium and oxygen, the latter by vacuum fusion.4 The solubility of the oxide in liquid iron is determined by visual observation of scum formation on the surface of the melt. Crucibles of MgO proved unsatisfactory because of partial reduction at the metal interface. Pure A12O3 crucibles were heavily blackened by the melt and could not be used at high concentrations of columbium. Silica crucibles were more satisfactory but these introduced some silicon into the melt thus necessitating an uncertain but small correction for its effect on the activities of the other solutes. In silica it was possible to observe the scum formation when the melt became saturated and there was no apparent reaction between scum and crucible. The procedure for saturated melts was as follows. The alloy charge composed of electrolytic iron and columbium grain was melted and held at constant temperature. The gas ratio H2O:H2 was progressively increased by raising the saturator temperature until a point was reached at which a bright film appeared on the surface and covered it completely. This film could be dissolved by raising the temperature of the melt and it reappeared when the temperature was lowered. Under a partial film covering, utilizing bare areas for temperature measurement, the melt was brought to equilibrium with the atmosphere by holding at temperature for about 1 hr as suggested by Dastur.5 INTERACTION IN THE MELT Several experiments were made without columbium to establish a base in silica crucibles. The results are shown in Table I. Except for one run, they agreed well with Floridis1 comparable results in other crucibles. The value of log K1 is taken from Table I as 0.58. This is slightly larger than Floridis&apos; result, probably because of less elaborate safeguards against thermal diffusion. Results obtained in the Fe-Cb-0 series in which no scum formed are shown in Table 11. The equilibrium ratio Kl is defined as ph2o/(ph2[%O]). It is related to the equilibrium constant K1 as follows:

Jan 1, 1962

University of Alabama University, Alabama Mining and Metallurgical Society Meets first and third Mondays each month JOHN MACLEOD MCKEE, President WILLIAM L. ALLMAN, Secretary J. R. CUDWORTH, Faculty Sponsor RICHARD L. BOWRON, Counselor University of Arizona Tucson, Arizona Millers&apos; Society LA MONT WEST, President AL WALLACH, Secretary J. B. CUNNINGHAM, Faculty Sponsor B. R. HATCHES, Counselor

Jan 1, 1939

By James M. Riddle

INTRODUCTION Block-caving mines are generally large operations. Calculating the quantity and value of mineral present and determining the economic limits to mining are complicated processes requiring much time and effort. If these processes are to be worthwhile, they must be accurate and reliable. Success in planning may increase the economic returns significantly. Since capital investments in block-caving mines are generally quite large, and development may span several years, quicker and more accurate methods of mine layout are very worthwhile to the mining industry. The purpose of this study is to develop an approach to the evaluation and layout of block-caving mines. The study included development of a simple approach to modelling ore reserves and a rapid, dynamic programming solution for optimum ultimate mining limits. TRADITIONAL APPROACHES TO BLOCK-CAVING MINE LAYOUT General discussion of techniques of calculating and valuing ore reserves can be found in the literature, (1-4). Mining limit approaches have been investigated by many and follow five general methods: 1, Moving cone method (5) 2. Graphroriented technique (6,7) 3. Dynamic programming technique (7,8,9) 4. Network flow method (10,11) 5. Pillar method (12) Of these investigations, only two were developed for underground mining applications, those of Sharp (9) and Riddle (11).

Jan 1, 1977

By W. Philippoff

ALTHOUGH Gaudin1 and more recently Sutherland2 have calculated the probability of collision of a falling mineral particle with a rising bubble, there is no published information concerning the details of the mechanism of attachment of a collector-coated particle to a bubble. During the past year the writer has developed a theory for the mechanism of attachment, which has been substantiated experimentally. Funds for the investigation and for some of the equipment used have been supplied by the Mines Experiment Station of the University of Minnesota. Motion picture studies of the phenomena involved in the collision between mineral particles and bubbles, such as those of Spedden and Hannan," show that the contact can be completed within 0.3 millisec. Formulas developed for rigid bodies have hitherto been used&apos; for the calculation of the motion of bubble and particle, but it is obvious that a bubble cannot be regarded as a rigid body. On the contrary, Spedden and Hannan&apos;s pictures show a great degree of deformation during the collision. The time of attachment was calculated as the time the particle drifted past the bubble. Time of Collision The theory presented in this paper enables calculation of the time of collision, using the concept that the bubble, or more generally, a liquid-air interface, acts as an elastic body. The elasticity, defined as the restoring force on a mechanical deformation, is caused by the surface tension and is the result of the principle of the minimum of free surface energy. It is well known that an elasticity together with a mass determines a frequency of vibration. The vibrations of jets and drops caused by the elasticity of the interface are known to comply exactly with the classical theory of capillarity.&apos; However, the vibrations of isolated bubbles, as distinct from foams, have not been investigated previously. The following equation, presented elsewhere,&apos; has been deduced for these frequencies: 3_____________________ fB = 9.20.vV.vn. (n-1).(n+2)/8 [I] in which fB is the frequency of a harmonic of the bubble in cycles per second, V the volume of the bubble in cc, n a number determining the order of the harmonic, and n = 2 the basic vibration. The first (basic) harmonic describes a change of the spherical bubble to an ellipsoidal bubble. The higher harmonics are more complicated, for the circumference of the bubble is divided approximately into as many parts as the order of the harmonic. As an example, Spedden and Hannan&apos;s published motion picture of a vibrating bubble corresponds to the sixth harmonic. Eq 1 shows that only the first and third harmonics are simple multiples (1 and 3), all the others being irrational fractions of the basic frequency. This means that the shape of the vibration can change with time and is in general unsym-metric in respect to the time axis. Such conditions prevail when there is a distributed elasticity or mass, as in the case of vibrating membranes or rods. The constant 9.20 is valid for water at room temperature, but a general solution involving the physical constants of the liquid has not been found. The case of the floating particle is much easier to treat than that of the bubble. It can be assumed that the elasticity is caused exclusively by the interface and that the mass is concentrated in the particle together with some adhering water. The following expression for the frequency of a system of one degree of freedom can be applied: fP = -1/2-vE/m [2] Here fp is the frequency of the particle vibration in cycles per second, E the elasticity in dynes per cm, and m the mass in grams. The classical theory of impact phenomena gives the time of collision during the striking of a spring (in this case the surface of the bubble) by a mass, as: t, = 2/f = nvm/E [3] It is now possible to develop an expression for the elasticity of a floating cylindrical particle. The force equilibrium of a cylinder floating end on at the air-liquid interface is given by the well-known equation (Poisson7 1831) P = /4 D2-pL-g-h + D.y sin a [4] which accounts for the buoyancy and the action of the surface tension where P is the force acting on the particle in dynes (weight-buoyancy), D the diameter of the cylinder in cm, PL the density of the liquid in grams per cc, g the acceleration of gravity = 981 cm per sec2, h the depression of the cylinder below the surface of the liquid in cm, y the surface tension in dynes per cm and a the supporting angles or the one required to insure equilibrium, a being smaller than the contact angle 0. Although demonstrated by Poisson, it has not

Jan 1, 1953

By W. Philippoff

ALTHOUGH Gaudin1 and more recently Sutherland2 have calculated the probability of collision of a falling mineral particle with a rising bubble, there is no published information concerning the details of the mechanism of attachment of a collector-coated particle to a bubble. During the past year the writer has developed a theory for the mechanism of attachment, which has been substantiated experimentally. Funds for the investigation and for some of the equipment used have been supplied by the Mines Experiment Station of the University of Minnesota. Motion picture studies of the phenomena involved in the collision between mineral particles and bubbles, such as those of Spedden and Hannan," show that the contact can be completed within 0.3 millisec. Formulas developed for rigid bodies have hitherto been used&apos; for the calculation of the motion of bubble and particle, but it is obvious that a bubble cannot be regarded as a rigid body. On the contrary, Spedden and Hannan&apos;s pictures show a great degree of deformation during the collision. The time of attachment was calculated as the time the particle drifted past the bubble. Time of Collision The theory presented in this paper enables calculation of the time of collision, using the concept that the bubble, or more generally, a liquid-air interface, acts as an elastic body. The elasticity, defined as the restoring force on a mechanical deformation, is caused by the surface tension and is the result of the principle of the minimum of free surface energy. It is well known that an elasticity together with a mass determines a frequency of vibration. The vibrations of jets and drops caused by the elasticity of the interface are known to comply exactly with the classical theory of capillarity.&apos; However, the vibrations of isolated bubbles, as distinct from foams, have not been investigated previously. The following equation, presented elsewhere,&apos; has been deduced for these frequencies: 3_____________________ fB = 9.20.vV.vn. (n-1).(n+2)/8 [I] in which fB is the frequency of a harmonic of the bubble in cycles per second, V the volume of the bubble in cc, n a number determining the order of the harmonic, and n = 2 the basic vibration. The first (basic) harmonic describes a change of the spherical bubble to an ellipsoidal bubble. The higher harmonics are more complicated, for the circumference of the bubble is divided approximately into as many parts as the order of the harmonic. As an example, Spedden and Hannan&apos;s published motion picture of a vibrating bubble corresponds to the sixth harmonic. Eq 1 shows that only the first and third harmonics are simple multiples (1 and 3), all the others being irrational fractions of the basic frequency. This means that the shape of the vibration can change with time and is in general unsym-metric in respect to the time axis. Such conditions prevail when there is a distributed elasticity or mass, as in the case of vibrating membranes or rods. The constant 9.20 is valid for water at room temperature, but a general solution involving the physical constants of the liquid has not been found. The case of the floating particle is much easier to treat than that of the bubble. It can be assumed that the elasticity is caused exclusively by the interface and that the mass is concentrated in the particle together with some adhering water. The following expression for the frequency of a system of one degree of freedom can be applied: fP = -1/2-vE/m [2] Here fp is the frequency of the particle vibration in cycles per second, E the elasticity in dynes per cm, and m the mass in grams. The classical theory of impact phenomena gives the time of collision during the striking of a spring (in this case the surface of the bubble) by a mass, as: t, = 2/f = nvm/E [3] It is now possible to develop an expression for the elasticity of a floating cylindrical particle. The force equilibrium of a cylinder floating end on at the air-liquid interface is given by the well-known equation (Poisson7 1831) P = /4 D2-pL-g-h + D.y sin a [4] which accounts for the buoyancy and the action of the surface tension where P is the force acting on the particle in dynes (weight-buoyancy), D the diameter of the cylinder in cm, PL the density of the liquid in grams per cc, g the acceleration of gravity = 981 cm per sec2, h the depression of the cylinder below the surface of the liquid in cm, y the surface tension in dynes per cm and a the supporting angles or the one required to insure equilibrium, a being smaller than the contact angle 0. Although demonstrated by Poisson, it has not

Jan 1, 1953