Diffusion and Oxidation of Solid Metals - Industrial & Engineering

Ind. Eng. Chem. , 1953, 45 (5), pp 907–911. DOI: 10.1021/ie50521a023. Publication Date: May 1953. ACS Legacy Archive. Cite this:Ind. Eng. Chem. 45, ...
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May 1953

INDUSTRIAL AND ENGINEERING CHEMISTRY

(IlOC) Teitel’baum, B. Ya, Gortalova, and Ganelina, S. G., Zhur. Obshchei Khim., 20, 1422-6. (111C) Teitel’baum, B. Ya., Gortalova, T. A., and Ganelina, S. G., J. Gen. Chem. U.S.S.R., 20, 1481-5 (1950). (112C) Thomaes, G., Physica, 17, 885-98 (1951). (113C) Timmerhaus, K. D., and Driokamer, H. G., J. Chem. Phys., 19, 1242-3 (1951). (114C) Troyer, A. de, Itterbeek, A. van, and Berg, G. S. van den, Physica, 17, 50-62 (1951) (in English). (115C) Troyer, A. de, Itterbeek, A. van, and Rietveld, A. O., Ibid., 17, 938-42 (1951) (in English). (116C) Udovenko, V. V., Airapetova, R. P., and Filatova, R. I., J.Gen. Chem. U.S.S.R., 21,1559-62 (1951).

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(117C) Uhlir, A., J. Chem. Phys., 20,463-72 (1952). (118C) Vargaftik, N. B., Izvest. Vsesoyuz. Teplotekh. Inst. im. Feliksa Dzerzhinskogo, 21, No. 1, 13-17 (1952). (119C) Wang, J. H., J. Am. Chem. Soc., 73, 510-3 (1951). (120C) Ibid., 73,4181-3 (1951). (121C) Washburn, E. R., and Dunning, H. N., J. Am. Chem. SOC., 73, 1311-13 (1951). (122C) Wesp, A., Erddl u.Kohle, 5,296-8 (1952). (123C) West, J. R., J.Phys. & Colloid Chem., 55, 402-5 (1951). (124C) Williamson, I., Nature, 167, 316-17 (1951). (125C) Winter, E. R. S., Trans. Faraday Soc., 47,342-7 (1951). (126C) Woodward, J. G., J. Colloid Sci., 6,481-91 (1952).

CHEMICAL RATE PROCESSES

Diffusion and Oxidation of Solid Metals C.

E. BIRCHENALL

Princeton University, Princeton, N. J.

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NVESTIGATION of diffusion in metallic solid solutions and the oxidation of metals and alloys has proceeded at a rapid pace since the end of World War 11. The intensity of effort is reflected in the large number of papers published in the past year in this very limited field. This review is based on papers published in 1952, plus a few papers published in 1951 which appeared in the abstract literature in 1952. Although this is the first systematic review of this AND ENGINEERING CHEMISTRY, the field to appear in INDUSTRIAL need for extension into the past is made unnecessary by several recent monographs and symposia. Barrer’s “Diffusion in and through Solids” (110)has been reissued during 1952, and in the absence of a hew edition designation it appears to be substantially the same as the 1941 volume. It must inevitably suffer from the omission of a large amount of very Pignificant work of all sorts which has been done subsequently. On the other hand, Jost’s new book on diffusion (3660) bears little resemblance to his earlier volume. The references seem to be complete through 1949, nearly complete for 1950, and to extend through a number of 1951 publications. The treatment covers all aspects of diffusion in solids, liquids, and gases and contains a chapter on reactions of the oxidation type. Three recent symposia are devoted partly or entirely to diffusion in solids and allied problems. The references contained in these volumes adequately bridge the gap between the monographs (110, 3 6 0 ) and the present article. “Atom Movements” (SD), the publication of a symposium held by the American Society for Metals in Chicago in 1950, concentrates on reactions in solid metals and contains both review material and, especially in the case of the theoretical contributions, several important original contributions. “Phase Transformations in Solids” (66‘0)is based on a symposium held a t Cornell University in 1948, but the papers were revised in 1950 before publication. I n this volume, Seitz reviews diffusion, including his kinetic theory. the result of a “Imperfections in Nearly Perfect Crystals” (6,90), conference a t Pocono Manor in 1950, includes much that relates directly to the mechanism of diffusion in metallic crystals. Occasional reference will be made to some of the individual papers in these symposia. Mott’s (410) discussion of diffusion, workhardening, recovery, and creep embodies the same point of view as the last symposium. A number of original contributions have dealt with mathemati-

cal solutions of the diffusion equations for special conditions of particular interest for metallic systemu. Stokes ( 6 7 0 ) found a solution for one-dimensional diffusion according to Fick’s law where the diffusion coefficient is a linear function of concentration. Wagner (6060)solved the problem for the case where the diffusion coefficient is an exponential function of concentration, which conforms more satisfactorily to the observed dependence for many metallic systems. Numerical comparisons are made with some appropriate cases previously reported. Frisch ( 2 7 0 ) analyzed the mathematics of diffusion controlled phase growth which is basic to heterogeneous reactions. Takagi (680)evaluated the diffusion component in solid reactions. A slightly different problem has been solved by Black and Doan (13D), who derived equations for diffusion under both thermal and concentration gradients acting together. I n this case the dependence of the diffusion coefficient on concentration has been neglected to facilitate handling the mathematics. Measurements of carbon diffusion in austenite have been made in the presence of a thermal gradient and a satisfactory agreement with the theory was found when the carbon diffusion coefficients determined in isothermal experiments and the thermal conductivities measured on homogeneous alloys were inserted in the theoretical equations. Babbitt ( 4 0 ) proposed a simple equation which permits diffusion in a wide range of states, from solid to gas, to be discussed in terms of a pressure function, which depends only on the thermodynamic properties of the system, and a resistive or frictional force, which must be derived from an assumed physical model. Guy (3160) examined interstitial diffusion, using carbon in Bustenite as the example, under the assumption that Fick’s law will apply without variation of the diffusivity with concentration if the concentration gradient is replaced by a thermodynamic potential gradient. Seith and Wever (6160)pointed out that although the concentration of a diffusing element may change discontinuously in a ternary system its activity must vary continuously. Although diffusivities may be calculated, accurate values must be determined experimentally. Nowick (4560) re-examined the experimental diffusion data from the point of view of Zener’s statistical thermodynamic theory for the frequency factor and entropy of activation described in Zener’s chapter in “Imperfections in Nearly Perfect Crystals”

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(610). He provides additional support for the widely held feeling that many of the data, particularly those of some age, are rather unreliable. Dienes (190)cited the negative entropy of activation for self-diffusion in tin as an exception to Zener's criterion, tending to favor his own correlation which allows for such values. The self-diffusion process in graphite has been studied experimentally by Feldman et al. (160)and theoretically by Dienes ($OD) in order to learn about the mechanism. A comparison of the theoretically calculated activation energies for interstitial, vacancy, and direct exchange mechanisms strongly favored the last a t about 90 kcal. per mole. In the experimental investigation this value was utilized to separate the grain boundary component and to estimate its activation energy. A variety of experimental methods have been used to obtain diffusion coefficients for a range of systems. Gatos and Azzam (SOD) utilized radioactive gold and autoradiography on an oblique section through the penetration zone in measuring the rate of selfdiffusion in gold. Their values agree well with those of McKay and seem to rule out values reported by Sagrubskii. T e r t (610) chose the internal friction method t o study the effects of alloying elements on the diffusion and precipitation of carbon in iron alloys, finding no effect for small amounts of nickel, molybdenum, chromium, and manganese, while vanadium had no effect on diffusion but a strong accelerating effect on precipitation. Le Claire (580)analyzed the problem of using anelastic measurements for the determination of diffusivities in substitutional solid solutions and applied his analysis to the data available on alpha brass. He discussed the utility and limitations of the method. Zwicker ( 6 6 0 ) utilized microhardness measurements to find the depth of chromium diffusion layers on nickel and iron. Several sets of investigators have taken advantage of the unique properties of germanium to measure diffusion rates by observing the motion of p-n junctions electrically. Fuller, Theuerer, and Van Roosbroeck (29D)observed the diffusivity of thermally produced acceptors by this means. Fuller and Struthers ( 2 8 0 ) found that the diffusion of Cue4 agreed reasonably well with the results of the preceding study. Dunlap and Brown (110)compared the method simultaneously with the radioactive method, following both the Sb1Z4and the p-n junction moving with it, and found good agreement. McAfee, Shockley, and Sparks (39D) applied a capacitance method, derived from a theory of Shoclrley, to measure the diffusivity of arsenic in germanium. Chang and Bennett ( 1 7 0 ) , using the permeability method to study hydrogen diffusion in iron alloys at high temperatures, found that nickel and molybdenum had little effect on the hydrogen diffusivity in alpha and gamma iron, chromium had little effect in gamma but reduced the rate in alpha iron. Weeton (610) employed conventional chemical methods in the determination of the concentration dependence of diffusivities in alpha cobalt-chromium solid solutions, as did Thomas and Birchenall ( 6 9 0 ) in studying the Thole solid solution range in copperpalladium and the high copper range in copper-nickel. In the latter system, the movements of inert markers were also observed and individual diffusivitics for copper and nickel estimated. Batz, Mead, and Birchenall ( I d D ) submitted new values for silicon diffusion coefficients in alpha and gamma iron. Lander, Kern, and Beach (37L))measured the solubility and diffusivity of carbon in nickel, over a range of temperatures. Sliflh, Lasarus, and Tomizuka (640)offered new values for the diffusion of antimony in silver to replace those of Seith and Peretti. Seith and Lopmann (5OD) compared the diffusion of silver, copper, magnesium, silicon, and zinc in a sintered aluminum rod with diffusion in a pure solid aluminum rod t o ascertain that there was no oxide film in the sintered product capable of restricting diffusion. Self-Diffusion Coefficients. In addition to the work of Gatos and Azzam cited above new determinations of self-diffusion coefficients have been reported. Perhaps the most significant

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were the results on self-diffusion in sodium, for it is for this metal that most of the energetic calculation suggesting the possibility of mechanisms other than the vacancy mechanism have been made-the four-ring rotation favored by Zener and the interstitial crowding favored by Paneth. Nachtrieb, Catalano, and Weil (410)obtained self-diffusion coefficients which yield activation entropies favoring a vacancy mechanism. I n a companion work, Nachtrieb, Weil, Catalano, and Lawson ( 4 9 0 ) measured the effect of hydrostatic pressures up to 8000 kg. per sq. cm. on selfdiffusion in sodium, finding a decrease in the diffusivity and an increase in activation energy accompanying an increase in pressure. They interpreted this study in favor of the vacancy mechanism, also. Buffington and Cohen ( 1 6 0 ) observed self-diffusion in alpha iron under an imposed uniaxial compressive stress and found that the diffusivity is independent of the strain but increases linearly with the strain rate, an effect attributed to an effective excess of vacancies generated by moving edge dislocations. Slifkin, Lazarus, and Tomiauka ( 6 3 0 ) confirmed the silver self-diffusion equation previously agreed upon by Johnson and by Hoffman and Turnbull. I n their polycrystalline samples a t low temperatures (576' C.) they observed a grain boundary component consistent with Hoffman and Turnbull's reported data. Nix and Jaumot ( 4 4 0 ) reported self-diffusion values for cobalt which are higher than those of Ruder and Birchenall by an amount which seems to be entirely contained in the different values for the effective absorption coefficients of the Co60radiations in cobalt reported in the two papers. Eckert and Drickamer (120)measured indium self-diffusion, Tl204 diffusion in indium, and In114 diffusion in gallium ( $ 3 0 ) . In each case they found no sharp discontinuity in the diffusivities at the melting points but a rapid increase slightly below the melting points in both single and polycrystals, although in the case of thallium in indium the rise began at considerably lower temperature in the polycrystal than in the single crystal. The effect of bombardment by an intense proton beam on selfdiffusion in silver was investigated by Johnson and Martin ( 3 4 0 ) , who concluded, in agreement with their observations, that the effects of the beam could not contribute a significant increase in the vacancy concentration, hence no measurable increase in the diffusion rate. Hoffman and Turnbull ( 3 3 0 ) found that small amounts of lead dissolved in silver increased the self-diffusion rate of silver with little or no effect on the activation energy. To account for the increase they postulated a second contributing mechanism in which silver and lead atoms exchange positions in the volume provided by a vacancy trapped by the lead atom. Surface. Surface diffusion got its share of attention as Menzel(4OD) observed the change of the surface structure on chemically etched copper single crystal spheres which permitted an estimate of the surface self-diffusion process. Winegard and Chalmers ( 6 3 0 )followed the spreading of an area plated with Ag"O on a silver surface by autoradiograph and observed an acceleration when the surface shape was changing at the same time. The acceleration was attributed to an excess of surface vacancies. Yanagisawa ( 6 4 D ) studied the rate of growth of amalgam layers on tin foil and the diffusion of mercury on etched and nonetched tin surfaces. Grain Boundary. Grain boundary diffusion was the subject of study by Bchter and Smoluchowski ( I D ) . Columnar copper Kith the [loo] directions nearly parallel in all crystals were plated with silver. Bfter diffusion, the preferential penetrations along the grain boundaries were revealed by etching and diffusion coefficients determined as a function of the relative orientation of the grains making up the boundary as well as the orientation of the boundary with respect to the copper lattices. For low boundary angles no preference was observed, but above a critical k n i t boundary diffusion exceeded volume diffusion, passing through a maximum for maximum orientation difference. The behavior was attributed qualitatively to a boundary made up of islands of fit and misfit as proposed by Rfott. In a discussion of this paper,

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Dawson ( 1 8 0 )suggested that the etching effects noted might have been the result of preferential precipitation of silver a t the grain boundaries, not preferential boundary diffusion. I n reply, Achter and Smoluchowski (%D)published an autoradiograph of Ag"0 in the copper grain boundaries after a diffusion treatment similar to the above. This result was independent of etching and of localized precipitation. Flanagan and Smoluchowski (266L))reported a similar study on zinc diffusion in columnar c o p per in which it was shown that the critical angle a t which preferential grain boundary diffusion begins is lower a t lower temperatures. Smolqchowski (660) examined the theoretical consequences of this behavior which can lead to very low or even apparently negative activation energies for boundary diffusion in the critical region. Kirkendall Effect. A great deal of effort has been devoted to the important task of elucidating the nature of the Kirkendall effect and the relations between vacancy diffusion and the porosity which develops during diffusion in many alloy couples. Nowick ( 4 6 0 ) found that a silver-zinc alloy quenched from 400" C. t o room temperature showed an anelastic aftereffect which was not present in a similar sample slowly cooled. Kauffman and Koehler (360) observed changes in resistivity of pure gold wires after very rapid quenching from high temperatures to liquid nitrogen temperatures which they attributed to the quenching-in of lattice vacancies. The most comprehensive work on the Kirkendall effect was that qf Seith and Kottmann ( 4 8 0 , 4 9 0 ) who made marker movement studies on the systems copper-nickel, silver-palladium, silver-gold, ' nickel, 58 % tungsten. gold-nickel, iron-nickel, and nickel-42 % In all except the last case marker movements were observed toward the first-named metal. A large amount of porosity was always found beyond the marker interface in the faster diffusing metal. Dimensional changes were not confined to the direction of diffusion, but large lateral changes occurred, especially in silver-palladium. Because of this failure to preserve the number of lattice planes in a given cross-sectional area, no exact relation is to be expected between the chemical diffusivity and the diffusivities for the individual components. The marker movements were reproducible only when the sandwich was arranged so that the porosity formed outside the marker interfaces, since the amount of porosity seemed t o be somewhat variable. There seemed to be a tendency for the porosity to concentrate a t a particular composition plane, making a barrier to volume diffusion which gave a minimum in the diffusivity-concentration curves. Use of a set of several parallel markers on both sides of a single interface showed that there was a tendency for the new planes to form a t a definite location on the slowly diffusing side of the markers. Seith, Heumann, and Kottmann ( 4 7 0 ) studied the movement ' to of an inert marker in a gold-silver alloy of about 50 atomic % confirm Darken's interpretation of Johnson's experiment. Ellwood ( 2 4 0 ) described porosity in a copper-nickel alloy for which he did not suggest a diffusional origin. Dimensional Changes. Barnes ( 1 0 0 ) studied the volume changes and porosity growth in the diffusion zone of coppernickel and copper-alpha brass couples and found that polygonization of the grains also occurs. Balluffi (60)confirmed this on a copper-nickel sandwich, showing that the finest subgrain size is near the diffusion interface, extending into the nickel side of the couple. Polygonization was attributed to plastic strains due t o dimensional changes normal to the diffusion direction. Balluffi and Alexander (60) showed that large dimensional changes occur normal to the diffusion direction by diffusing silver into gold wires from the vapor phase and observing the changes in length of the wires. The same authors ( 7 0 ) compared the weight loss on dezincing a piece of alpha brass with the density change and concluded that about 40% of the maximum possible porosity remained. Similar results were found for silver-palladium, cop-

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per-nickel, and silver-gold. Porosity in sandwich-type couples was found to be independent of the thickness of the external layer down to 0.055 inch. On zincing a piece of copper no porosity developed, b u t adding silver from the vapor phase to a gold wire produced appreciable porosity. I n another paper ( 8 0 ) , with the aid of the movement of tungsten particle markers advantage was taken of the absence of porosity on zincing copper to measure individual copper and zinc diffusivities. Hersh ( 3 2 0 ) measured the shrinkage of the external faces of brass during dezincing to demonstrate the large residual porosity. Buckle and Blin ( 1 4 0 ) found that the holes formed during diffusion in copper-aluminum were regular octahedra with [111]faces. I n the case of copperalpha brass the pores were rounded. Microhardness, which was lower on the brass side of the interface than normally expected, was used to show the extent of diffusion and to supplement metallography as a means of detecting porosity. Barnes ( 9 0 ) and Butler and Hoar ( 2 6 0 ) both demonstrated that interdiffusion of two metal .powders can generate porosity a t such a rate as to decrease the initial density of a compact without assistance from included gases. Barnes pointed out that in pure metals or homogeneous alloys this increase cannot occur even though some existing pores may grow larger a t the expense of smaller pores. Butler and Hoar found that raising the temperature of their copper-nickel compacts to 775" C. causcd sintering without initial swelling, while below 700' C. interdiffusion produced fissures without subsequent sintering. Thus, they concluded, diffusion is not important in the sintering phase of densification.

Oxidation It is convenient t o consider the papers dealing with oxidation under two subdivisions-papers which are concerned primarily with the oxidation of pure metals and those which seek t o understand the oxidation behavior of alloys. Pure Metals. Waber ( N E )contributed a review article on the scaling of metals and alloys in which he classifies metals according to the temperature range in which they conform t o each of the four types of rate laws-logarithmic, cubic, parabolic, and linear. His primary concern was with the conditions leading to a change in the time dependence of oxidation with changing temperature. He considered the cubic rate law specifically in another paper (34E), and with Sturdy, Wise, and Tipton ( 3 6 E ) showed that the oxidation of tantalum underwent a change in rate law a t about 320 O C. from logarithm t o parabolic. Cubicciotti studied the oxidation of uranium (11E) and cerium (12E). The former metal oxidized according t o a parabolic law below 165" C., according to a linear law from 165' t o 215 O C., and a t an accelerating rate above 215" C. Cerium also showed the parabolic t o linear transition a t about 125' C. It has the most rapid parabolic rate that is known. Morton and Baldwin (29E) made an extensive investigation of the oxidation of titanium in air, and reported on the morphology and crystal structure of the products. Arkharov and Luchkin ( 1 E ) sought to explain the role of nitrogen during high temperature oxidation of titanium in air by referring this behavior to that observed during oxidation in pure oxygen. They measured a difference in the lattice parameters of the titanium dioxide phase which was ascribed t o partial replacement of oxide ions by nitride ions plus additional lattice site vacancies above 900" C. Knowledge of the scaling of lead in air was extended to the although the measuresolid phase by Weber and Baldwin (38E), ments also covered temperatures a t which the lead was liquid. The product of the parabolic oxidation of solid lead was beta lead oxide only. Scaling of the liquid gave a more complex rate law and other products. Moore and Lee (.ME) showed t h a t oxidation of nickel in 10 cm. of mercury pressure of pure oxygen conforms well to the para-

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bolic law over the temperature range 400" to 900' C. The mechanism was discussed. Between 700" and 900" C. chromium oxidized to give only chromic oxide unless the oxygen pressure was high enough to convert the outer layer to chromium trioxide. Gulbransen and Andrew (15E) observed nearly parabolic rates at pressures which gave rise to chromic oxide alone. Using a high temperature electron diffraction camera, Gulbransen and McMillan (17.73)found orily normal zinc oxide lines for the oxide formed on zinc and only normal cuprous and cupric oxide lines for oxides formed on copper. They believed the extra reflections reported b y others were due to the oxides of impurities concentrated in the surface layer. Moore (,%E) re-examined the mechanism of oxidation of zinc theoretically, concluding that interstitial zinc ions do not arise by thermal dissociation from interstitial zinc atoms but as a result of the transfer of electrons from interstitial zinc atoms to how it might be posadsorbed oxygen. He also showed ($5~3') sible for a parabolic rate law to occur which is not diffusion controlled if a particular space distribution of lattice defects is produced as a result of oxygen adsorption. Moore and Selikson reported a correction ( B E ) to their earlier paper ( d 7 E ) on the diffusion of copper in cuprous oxide. The earlier work had shown that the same diffusion coefficients for copper are obtained whether the cuprous oxide is homogeneous or growing on a metallic copper substrate. Bouillon (4E-5E) studied the influence of temperature, the nature of the oxidation isotherm, and the influence of copper microstructure on the oxidation of pure copper. Microscopic measurement of scale thickness was used to check the thickness obtained by electrochemical reduction of the scale. Hauffe and Engell ( 1 5 E , 19E) described, qualitatively and quantitatively, the effects on the structure and properties of oxides produced by the adsorption of oxygen. Hauffe and Pfeiffer (2OE) considered these effects as a part of the over-all oxidation process. They discussed the results obtained between 850 and 1000° C.for the oxidation of iron in mixtures of carbon monoxidecarbon dioxide chosen to restrict the products to wustite only. Their results probably should be considered together with the observations of BBnard and Bardolle ($E, S E ) on the nucleation of wiistite on iron surfaces at 850" C. in low oxygen pressures. The latter showed that the number and shape of the oxide particles formed per unit area on a single grain seemed to depend on the crystallographic orientation of the exposed face of the grain. The nucleation rate had P strong pressure dependence. Gulbransen and Ruka (1823)made a thorough study of the orientation relations between the iron oxide phases and the underlying metal or oxide phases, whether formed during oxidation or solid reaction in the scale as a result of change in temperature or pressure. They showed that the orientation relationships did not depend on the crystallographic nature of the exposed face. The relationships agreed with those observed previously bJr others, and the relationship between iron and magnetite was shown to be the same as that between iron and wustite. B y exceptionally fine metallographic work, Paidassi (30E, 31E) demonstrated that hematite is present on scales on iron a t temperatures as low as 700' C. as a continuous layer, and established with much improved accuracy the proportion of the scale occupied by each of the three oxides. He confirmed that each grows according to a parabolic rate law, Microporosity, needlelike in shape, was observed running in the growth direction. The question of how scales behave when they attain thicknesses of the order of the thicknesses of the oxidizing iron substrate or of the radius of curvature of the underlying area has been approached by Dunnington, Beck, and Fontana (14E). They repeated Pfeil's experiment using oxide markers and concluded that w k t i t e growth is partially due to oxygen transport. The problem of the continuity and adherence of the oxide scale is especially important from the practical point of view.

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Alloys. Wagner ( S 7 E ) made a theoretical analysis of the diffusion processes determining the oxidation rates of alloys under the restrictive conditions that only an external scale consisting of a single phase of pure oxide is formed. Two types of cases were compared with the theory, the first in which the alloy consisted of a base metal and a noble metal and the second in which the two base metals compete to form oxide. The possible ways in which real systems may deviate from the theoretical model were discussed, Pfeiffer and Hauffe (3823) investigated the influence of small additions of chromium and silver to nickel on the rate of oxidation. They also measured the rate of oxidation of nickel at 1000' C. in an atmosphere which contained lithium oxide vapoi and of titanium a t 800' C. in an atmosphere containing tuiigskri trioxide vapor. Both vapor additions markedly decreased the oxidation rate. They discussed the role of oxide eutectics in accelerating oxidation. Oxidation of several phases of the copper-tin system covering 3 composition range of 5.85 t o 37.15 weight % tin from 500" to 800" C. was studied by De Carli and Collari ( I S E ) . A coppel2y0 beryllium alloy was oxidized over the range 200' to 800" C. by Brouckere and Hubrecht (8E). The products were identified microscopically and by diffraction. Coulometric estimates of cuprous and cupric oxides were made and evidence for a continuous film of beryllium oxide was found. Hubrecht (WIE) showed how an oxidation a t very low pressure above 600' C. could produce a beryllium-rich film which protected the metal in normal oxidizing atmospheres a t 400" or 500 O C. Collari (10E) found that 0.2% phosphorus added to iion led to the production of a protective phosphate-rich layer near thr. metal-oxide interface when oxidation was carried out between 800" and 900" C. Iitake, Nakayama, and Sekiguchi (WSE) oxidized iron-chromium alloys and iron-nickel-chromium and iron-nickel-chromium-molybdenum stainless steels a t 900 O C. The outer protective coating of mixed spinels and (Fe,Cr)s09 oxides were removed with solder flux to expose layers of nickel oxide and nickel particles on the nickel-containing alloys. In addition, the molybdenum-containing alloys had molybdenum trioxide a t sufficiently high vapor pressure to destroy adhesion of the film. The applicability of x-ray fluorescent analysis to the study of the composition of oxides on iron-nickel and iron-chromium alloys and a stainless steel was demonstrated by Koh and Caugherty ( M E ) . The succession of layers of oxide and underlying metal surface composition variations were described. Caplan and Cohen (QE)oxidized three iron alloys containing 11 4, 15.8, and 26.5y0 chromium and small quantities of carbon, manganese, silicon, and nickel in dry or wet air at temperatures between 870' and 1095 O C. The scales contained a spinel oxide, a rhombohedral oxide, and silica in the form of alpha cristobalite The rate curves showed periods of rapid oxidation alternating with periods in which the scale was highly protective. Preece and Lucas (S3E) observed the behavior of cobalt base binary alloys containing 10 to 4oyOchromium, 5 to 15y0 tungsten, 5 to 15% molybdenum, 5% aluminum, and 4Oy0nickel, and nickcl base alloys containing 5 to 15% tungsten, 5 to 15y0molybdenum, and 5% aluminum in simulated gas turbine atmospheres containing 3.5y0 carbon dioxide, 3.3% water vapor, 0.06% sulfur dioxide, and the remainder air slightly enriched in nitrogen. Pure cobalt and nickel were tested as standards. Products were identified by x-ray diffraction. They concluded that the formation of spinels in these systems was undesirable. Molybdates were found to undergo transformation on cooling which seriously disrupted the scale. Occurrence of more than one oxide in the scale was undesirable, and low-melting mixtures of oxides were to be avoided. Brasunas and Grant (723) found that during oxidation of iron base alloys of l6y0chromium, 25% nickel, 6% molybdenum, and 16% chromium, 25% nickel, 6% vanadium alloy content in one atmosphere of pure oxygen from 780' to 1150" C., specimen tem-

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perature rises of 5 O to 30 O C. above furnace temperature occurred. The scales had about 27% porosity. Little vapor loss of volatile oxide constituents was observed. Elimination of molybdenum gave good oxidation-resistant properties t o the alloy, while increasing nickel content, substitution of cobalt for nickel, or addition of 3% silicon were all helpful. The use of platinum wire markers applied to several unoxidiaed metal specimens were found in the following positions after complete oxidation:

Armoo iron. Wires embedded completely with only a very small fraction of the total oxide lying within the markers Iron-2% silicon-2% aluminum alloy. Wires completely embedded with no oxide inside Iron-16% chromium-25% nickel-6% vanadium alloy. Wires on outside of scale, all oxide inside *’

This indicated a great change in transport mechanism in the last case as compared with the first two.

Literature Cited Diffusion Achter, M. R., and Smoluchowski, R., ’J. Appl. Phys., 22, 1260 (1951). Ibid., 23, 373 (1952). Am. SOC.Metals, Cleveland, “Atom Movements” 1951. Babbitt, J. D., Can. J. Phys., 29, 427 (1951). Balluffi, R. W., J . A p p l . Phys., 23, 1407 (1952). Balluffi, R. W., and Alexander, B. H., Ibid., 23,953 (1952). Ibid., p. 1237. Balluffi, R. W., and Alexander, B. H., J . Metals, 4, Trans. 1315 (1952). Barnes, R. S., Phil. Mag., 43,1121 (1952). Barnes, R. S., Proc. Phys. SOC.(London),65B, 512 (1952). Barrer, R. M., “Diffusion in and through Solids,” Cambridge, Cambridge University Press, 1952. Batz, W., Mead, H. W., and Birchenall, C. E., J . Metals, 4, Trans. 1070 (1952). Black, J. E., and Doan, G. E., Trans. Am. SOC.Metals, 44, 452 (1952). Buckle, H., and Blin, J., J . Inst. Metals, 80,385 (1952). Buffington, F. S., and Cohen, M., J . Metals, 4, Trans. 859 (1952). Butler, J. M., and Hoar, T. P., J . Inst. Metals, 80, 207 (1952). Chang, P. L., and Bennett, W. D. G., J . Iron Steel Inst., 170,205 (Sept. 10, 1952). Dawson. M. H.. J. A w ~ l Phus.. . 23.373 (1952). Dienes, G. J., Idid., 22;848 (i951). Ibid., 23, 1194 (1952). Dunlap, W. C., Jr., and Brown, D. E., Phys. Rev., 86, 417 (1952). Eckert, R. E., and Drickamer, H. G., J. Chem. Phys., 20, 13 (1952). Ibid., p. 532. Ellwood, E. C., Nature, 170, 580 (1952). Feldman. M. H.. Goeddel. W. V.. Dienes.’ G. J.. and Gossen - W., J . A p p L P h y s . , 23, i200 (1952). Flanagan, R., and Smoluchowski,R., Ibid., 23,785 (1952). Frisch, H. L., 2.Elektrochem., 56, 324 (1952). Fuller, C. S., and Struthers, J. D., Phys. Rev., 87,526 (1952). Fuller. C. S.. Theuerer. H. C.. and Van Roosbroeok, R., Ibid., 85, 678 (1952). Gatos, H. C., and Azzam, A., J . Metals, 4, Trans. 407 (1952). Guy, A. G., Trans. Am. SOC. Metals, 44,382 (1952). Hersh, H. N., J . Appl. Phys., 23, 1055 (1952). Hoffman, R. E., and Turnbull, D., Ibid.. 23,1409 (1952). Johnson, R. D., and Martin, A. B., Ibid., 23, 1245 (1952). Jost, W., “Diffusion in Solids, Liquids, Gases,” New York, Academic Press, 1952. Kauffman, J. W., and Koehler, J. S., Phys. Rev., 88, 149 (1952) Lander,’J. J., Kern, H. E., and Beach, A. L., J . Appl. Phys., 23, 1305 (1952). Le Claire, A. D., Phil. Mag., 42, 673 (1951). McAfee, K. E., Shockley, W,, and Sparks, M., Phys. Rev., 86, 137 (1952). Menzel, E., 2.Physik, 132, 508 (1952). Mott, N. F., Inst. intern. phys. Solvay, 5th Conseil phys., Univ. Bruxelles, Etat solide, Rapp. et disc., 1951, p. 515. Nachtrieb, N. H., Catalano, E., and Weil, J. A., J . Chem. Phys., 20, 1185 (1952). Nachtrieb, N. H., Weil, J. A. Catalano, E., and Lawson, A. W.. Ibid.. 20.1189 - ,- - - - (1952). (44D) Nix$F. CI,and Jaumot, F. E.; Jr., Phys. Rev., 83, 1275 (1951). I

911

(45D) Nowick, A. S., J . Appl. Phys., 22, 1182 (1951). (46D) Nowick, A. S., Phys. Rev., 82, 551 (1951). (47D) Seith, W., Heumann, T., and Kottmann, A,, Naturwissenschaften, 39, 41 (1952). (48D) Seith, W., and Kottmann, A., Angew. Chem., 64,379 (1952) (490) Seith, W., and Kottmann, A., Naturwissenschaften, 39, 40 (1952). (50D) Seith, W., and Lopmann, G., 2. Elektrochem., 56,373 (1952). (61D) Seith, W., and Wever, H., 2.Elektrochem., 55, 380 (1951). (52D) Shockley, W., Hollomon, J. H., Maurer, R., and Seitz, F., editors, “Imperfections in Nearly Perfect Crystals,” New York, John Wiley &Sons, 1951. (53D) Slifkin, L., Lazarus, D., and Tomizuka, T., J. A p p l . Phys., 23, 1032 (1952). (54D) Ibid., p. 1405. (55D) Smoluchowski, R., Phys. Rea., 87, 482 (1952). (56D) Smoluchowski, R., Mayer, J. E., and Weyl, W. A., editors, “Phase Transformations in Solids,” New York, John Wiley & Sons, 1952. (57D) Stokes, R. H., Trans. Faraday SOC.,48,887 (1952). (58D) Takagi, Katsuki, J . Chem. SOC.Japan, Pure Chem. Sect., 72, 1056 (1951). (59D) Thomas, D. E., and Birchenall, C. E., J . Metals, 4, Trans. 867 (1952). (60D) Wagner, C., Ibid., 4, Trans. 91 (1952). (61D) Weeton, J. W., Trans. Am. SOC.Metals, 44,436 (1952). (62D) Wert, C. A., J . Metals, 4, Trans. 602 (1952). (63D) Winegard, W. C., and Chalmers, B., Can. J. Phys., 30, 422 (1952). (64D) Yanagisawa, M., 6yy8 Butsuri (J.Appl. Phys.), 21, 18 (1952) (65D) Zwicker, U., Metalloberfldche, A6, 81 (1952). Oxidation (1E) Arkharov, V. I., and Luchkin, G. P., Doklady Akad. Nauk S.S.S.R.,83,837 (1952). (2E) Bardolle, J., and BQard, J., Compt. rend., 232, 231 (1951). (3E) BQnard,J., and Bardolle, J., Ibid., 232,2217 (1951). (4E) Bouillon, F., Bull. SOC. chim. Belges, 60,337 (1951). (5E) Ibid., p. 451. (BE) Ibid., 61, 3 (1952). (7E) Brasunas, A. de S., and Grant, N. J., Trans. Am. SOC.Metals, 44. 1117 (1952). (8E) Brouhkere, L. de, and Hubrecht, L., Bull. SOC. chim. Belges. 61, 101, (1952). (9E) Caplan, D., and Cohen, M., J.Metals, 4, Trans. 1057 (1952). (10E) Collari, N., Met. ital., 44, 97 (1952). (11E) Cubiooiotti, D.. J. Am. Chem. SOC., 74, 1079 (1952). (12E) Ibid., p. 1198. (13E) De Carli, F., and Collari, N., Met. ital., 44, 1 (1952). (14E) Dunnington, B. W., Beck, F. H., and Fontana, M. G., Corrosion, 8 , 2 (1952). (15E) Engell, H. F., and Hauffe, K., Metall, 6,285 (1952). (16E) Gulbransen, E. A,, and Andrew, K. F., J . Electrochem. SOC., 99, 402 (1952). (17E) Gulbransen. E. A.. and McMillan. W. R.. Ibid.. 99. 393 (1952). (18E) Gulbransen, E. A,, and Ruka, R., Ibid., 99,360 (1952). (19E) Hauffe, K., and Engell, H. J., 2. Elektrochem., 56,366 (1952). (25E) Hauffe, K., and Pfeiffer, H., Ibid., 56, 390 (1952). (21E) Hubrecht, L., Bull. SOC. chim. Belges, 61,205 (1952). (22E) Iitake, I., Nakayama, T., and Sekiguchi, K., J . Sci. Research Inst. (Tokyo),45,57 (1951). (23E) Koh, P. K., and Caugherty, B., J . A p p l . Phys., 23, 427 (1952). (24E) Moore, W. J., J . Chem. Phys., 20,764 (1952). (25E) Moore, W. J., Phil. Mag., 43, 688 (1952). (26E) Moore, W. J., and Lee, J. K., Trans. Faraday SOC.,48, 916 (1952). (27E) Moore, W. J., and Selikson, B., J. Chem. Phys., 19, 1539 (1951). (%E) Ibid., 20, 927 (1952). (29E) Morton, P. H., and Baldwin, W. &I., Jr., Trans. Am. SOC. Metals, 44, 1004 (1952). (30E) Paidassi, J., Bol. SOC. chilena quam., 3, 55 (1951). (31E) Paidassi, J., Ing. quam., Univ. Concepcion, Chile, 10, No. 10, 5 (1951). (32E) Pfeiffer, H., and Hauffe, K., 2.Metallkunde, 43,364 (1952). (33E) Preece, A., and Lucas, G., J.Inst. Metals, 81,219 (1952). (34E) Waber, J. T., J . Chem. Phys., 20,734 (1952) (35E) Waber, J. T., Metal Progr., 62, No. 3, 76 (1952). (36E) Waber, J. T., Sturdy, G. E., Wise, E. M., and Tipton, C. R., J . Electrochem. SOC.,99, 121 (1952). (37E) Wagner, C., Ibid., 99, 369 (1952). (38E) Weber, E., and Baldwin, W. M., Jr., J . Metals, 4, Trans. 854 (1952).