Many studies have been carried out on the stress corrosion cracking susceptibilty and the dislocation arrangement of alloys, particularly in regard to the difference of stress corrosion susceptibility between the alloys which show planar and cellular arrays of dislocations by tensile deformation.
In this study, fracture time tests have been performed on the prestrained brass having various dislocation arrangements.
The dislocation arrays observed in 70-30 brass after tensile deformation are planar at a low strain and cellular at a high strain, irrespective of the prestraining temperature.
The stress corrosion susceptibility is increased by prestraining for all the alloys investigated. The relation between stress corrosion susceptibility and the amount of prestrain shows a different dependence on prestraining temperature. The results indicate that the planar arrays of dislocations are not always more susceptible than the cellular arrays.
A small addition of silicon to 70-30 brass increases the stress corrosion resistance of the annealed specimens. But it is shown that prestraining causes a remarkable increase in the susceptibility of 70-30 brass containing 0.46 wt% Si.

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The rate of growth and the interlamellar spacing of the isothermally transformed pearlite in a high purity eutectoid carbon steel and in two commercial manganese steels were measured, and the process of the pearlite growth was studied from the points of view of the carbon diffusion controlled mechanism and the interface migration mechanism. Referring to the reliable data of several experiments carried out by other writers, the following results were obtained:
(1) It is reasonable to think that the rate controlling process of pearlite growth in the high purity eutectoid carbon steel is the diffusion of carbon in austenite along the interface between austenite and pearlite.
(2) In the high purity eutectoid carbon steel, the interlamellar spacing measured shows a value ten times greater than the minimum interlamellar spacing calculated from the thermodynamical limit in the pearlite transformation. The interlamellar spacing which corresponds to the maximum growth rate of pearlite is two times greater than the minimum interlamellar spacing, and it does not agree with the measured spacing. A relation between the measured growth rate (r) and the calculated maximum growth rate of pearlite (r_p) is given by r=0.36r_p.
(3) The growth rate of pearlite is decreased considerably by the addition of manganese. This phenomenon may in part be attributed to the decrease of ΔF₀ with the increase in manganese content.
(4) The interlamellar spacing of pearlite is scarcely influenced by the addition of less than about 1 weight percent manganese.
(5) In the temperature range of the non-partitioned pearlite, it is considered that the rate controlling process of pearlite growth in the steel containing less than about 0.5 weight percent manganese is similar to that of high purity eutectoid carbon steel, but with more than about 0.5 weight percent manganese, the steel shows the austenite-pearlite interface migration mechanism; namely, its rate is controlled by the short range diffusion of iron atoms at the austenite-pearlite interface.

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High temperature oxide films and sealability of Fe-42 Ni-6 Cr alloys containing Al, Mn and Si, which is used for soft glass sealing, have been investigated by mean of microscope observation, kinetic study and X-ray microanalysis.
In the case of Al addition, the alloy oxidized in wet hydrogen shows good adherence between metal and oxide film. The oxide film formed on the alloy surface consists of Cr₂O₃ and (Fe, Mn) O·Cr₂O₃ as in the case of the alloy to which Al was not added. The activation energy of the alloy changes at 1100°C, amounting to 45 kcal/mol on the high temperature side and 11.6 kcal/mol on the low temperature side.
It is shown that the Mn concentration tends to decrease at the boundary between the metal and the oxide film and the Si concentration is high at the boundary.
Internal oxidation was observed in the Al-containing alloy which was oxidized in wet hydrogen. By etching in aqua regia, etch pits found. A Liesegang band of etch pits was observed in one case, and clustering of etch pits over a certain width in the other.

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Fe-18 Cr alloy which is used for glass sealing was oxidized in air and wet hydrogen, and the oxide film formed on the alloy surface was investigated by means of SEM, EPMA and X-ray diffraction. The results obtained are as follows.
(1) Oxide films obtained in both atmospheres consist chiefly of Cr₂O₃ and (Fe, Mn)O·Cr₂O₃, but show a distinct difference in morphology.
(2) Oxide films obtained in air have a random orientation, but those in wet hydrogen have a preferred orientation.
(3) Oxide films obtained in both atmospheres are formed in the order of Cr₂O₃ and (Fe, Mn)O·Cr₂O₃ on the alloy surface. The principal diffusion elements in glass on glass sealing are Mn and Fe.
(4) Activation energy for oxidation in air changes at about 1000°C, amounting to 103.5 kcal/mol on the high temperature side and 23.6 kcal/mol on the low temperature side. Oxidation rate constants in wet hydrogen change linearly between 800°C and 1250°C, the activation energy for oxidation being 40.6 kcal/mol. The oxidation rate constant changes in proportion to the exponent of 1/5 of partial pressure of oxygen.

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Matastable β titanium alloys were made by quenching after solution treatment and then aged after chemical plishing. It was observed that there were three different decomposition reactions in the metastable β phase by the condition of chemical polishing. In order to investigate the cause of these reactions, hardness measurement, X-ray diffraction, electron probe X-ray microanalysis and gas analysis were performed. The results obtained are summarized as follows: (1) In Ti-10 Fe and Ti-8.5 Mn alloys aged below 450°C following after chemical plishing, three different decompositions, that is, (a) β→β+ω, (b) β→β+α and (c) β→β+cluster→β+α, were observed depending on the duration of chemical polishing. However, the reaction, (c) was not observed in the Ti-16 Mo and Ti-20. 5 V alloys. (2) It was concluded that the difference among the three decomposition reactions was caused by hydrogen which dissolved into the metastable β phase during the process of chemical polishing. (3) From X-ray diffraction patterns for the Ti-10 Fe alloys, it was concluded that during the first step of (c) reaction Fe atoms of alloys clustered onto the {100} planes of the β phase.

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The stress corrosion cracking of single crystals and bicrystals of Al-1% Cu alloys, prepared by the Bridgman method, was examined with reference to slip characteristics and misorientation of grain boundary.
Preferential corrosion attack was clearly observed along (100) traces in both single and bicrystal specimens. Stress corrosion cracking occurred along these (100) traces in the single crystals. Therefore, the distribution of slip lines and the slip step height on the specimen surface gives little influence on the stress corrosion cracking in this case.
On the other hand, cracking always occurred at the grain boundary, regardless of the degree of misorientation in the bicrystals. Fracture time decreased with the increase of tilt and twist angles when a constant normal stress and shear stress were given to the grain boundary.

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The mechanism of anodic dissolution for various heat-treated aluminium alloys under plastic deformation was examined in a 1% ammonium borate solution. The results obtained are as follows:
(1) The increase of anodic dissolution current by plastic deformation depends on the dissolution of newly emerged slip planes and the decrease of it depends on the repair of the surface film.
(2) The silicon content in aluminium alloys seems to have an important effect on anodic dissolution in regard to the formation or repair of the surface film.
(3) Properties and distribution of precipitates are also related to the disolution rate of alloys.
(4) The corrosion of aluminium alloys is controlled by a cathodic reaction, i. e. the reduction of oxygen, below 60°C in the test solution. But the cathodic reaction changes to hydrogen evolution with the depolarization of the anodic reaction above 60°C.
(5) When stress is applied, the apparent activation energy Q for the dissolution of Al-4% Cu alloy is estimated about 16 kcal/mol under the condition of strain rate \dotε=5%/min and above 50°C. But when no stress is applied, Q is about 7 kcal/mol. This is because the alloy can actively dissolve in the former by the rupture of the surface film caused by applied stress at high temperature, but the dissolution may be diffusion-controlled in the latter.

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The permeation of hydrogen in low carbon steel was measured at room temperature by an electrochemical method. The transient response was analysed with special attention to the trap effect of impurities and the surface effect of environment. In order to detect the intrinsic diffusion of hydrogen, the diffusion theory was applied only to the initial transient of permeation that represents the fast component due to lattice diffusion. Furthermore, the error caused by surface reaction was eliminated by examining the size dependence of apparent diffusivity. As a result, the true diffusivity of hydrogen in iron was determined to be 7×10⁻⁵ cm²/sec at 20°C, which is independent of defects in the specimen and conditions of the measurement. The lattice solubility of hydrogen was also estimated in the super-saturated state provoked by an elecrochemical condition.

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The effects of temperature, strain rate and grain size on the flow stress of commercial Ti-5 Al-2.5 Sn (α), Ti-6 Al-4 V (α+β) and Ti-5 Al-2 Cr-1 Fe (α+β) alloys with 0.31∼0.57 at% O_eq interstitial solute content were investigated over the temperature range of 77 to 700°K. Thermal activation analysis revealed the values of H₀ and v_T0′^*, to be \simeq0.2μb³ and 70∼80b³. The force-distance curve and the effect of interstitial content on the effective stress at 0°K are similar to those for unalloyed alpha titanium, indicating that the rate controlling mechanism in the present alloys is the thermally activated overcoming of interstitial solute atoms and also that substitutional solute atoms increase the strength of the alloys only through the athermal component of the flow stress.

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The potential of the Graphite-Aluminum composites as a high strength to density material has been demonstrated to be retained up to the temperature near the matrix’s melting point. Uniaxial tensile tests at elevated temperatures and creep rupture tests have shown that the strength of carbon fiber-reinforced aluminum is very slightly degraded at high temperature.
But Nickel, the carbon fiber coating which is intended to make the fiber wet to the matirx and to prevent the formation of Al-carbide, reacts with molten aluminum and becomes brittle intermetallic compounds such as Al₃Ni. The compounds may act as a crack source and lower the toughness of the composite.
Fatigue properties of the material are also investigated. Fatigue strength at room temperature showed a value of about 60% of static strength.

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Plastic flow during the phase transformation has been studied in ferritic and pearlitic ductile cast irons. Specimens subjected to a constant load were cycled through the ferrite+graphite\ ightleftharpoonsaustenite transformation, and pearlite\ ightleftharpoonsaustenite transformation respectively. Transformation plasticity, characterized by the linear relationship between the transformation strain per cycle and the externally applied stress (i.e., strain rate sensitivity exponent, m is 0.8) was observed for both irons. The occurrence of ‘Superplasticity’ is thus demonstrated for dectile cast iron. For both irons, the plastic transformation strain on heating was larger than that on cooling. On the pearlitic ductile cast iron during heating, the relationship between log stress and log strain rate remained linear to a much higher strain rate than in other cases. On the ferritic ductile cast iron, it is suggested that the plastic transformation strain depends on the amount of austenitizing in the ferrite matrix.

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Internal friction measurements by an inverted torsional pendulum apparatus with the frequency of about 1 Hz were carried out in the temperature range of 300 to 850°C for Cu-0.71% Ag, -1.77% Ag, and -3.55% Ag alloys.
In 0.71% Ag alloy a grain boundary peak was observed at about 550°C; the activation energy was estimated at 37±5 kcal/mol. In 1.77% Ag alloy a peak appeared at 660°C, but it showed no grain size dependence. In 3.55% Ag alloy, besides a grain boundary peak at about 550°C, another peak was observed at 710°C on heating and at 660°C on cooling. The latter peak, the height of which depended on the frequency and the cooling rate, was supposed to be a precipitation peak other than the relaxation-type peak. The height of the peak at 550°C decreased with increasing cooling rate, presumably due to the suppression of grain boundary migration by supersaturated solute atoms near the grain boundary.

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Measurements of Young’s modulus at −150∼400°C and of rigidity modulus, thermal expansion and hardness at room temperature have been carried out for Mn-Ni-Mo alloys in the states of cold working and heat treating. In the ternary alloys of 60∼95% Mn, 0∼40% Ni and 0∼25% Mo slow cooling after subjected to heating for 1 hr at 950°C, anomalous changes associated with antiferromagnetic\ ightleftarrowsparamagnetic transformation are observed on the Young’s modulus vs temperature curves. Young’s modulus at room temperature do not show any great difference by the cold-worked and heat-treated states. However, the value increases in general with increasing manganese or molybdenum content. The temperature coefficient of Young’s modulus varies remarkably by the difference in the states of heat treatments and alloy composition. The temperature coefficient of Young’s modulus exhibits a large positive maximum against composition, indicating that the ternary alloys possess the Elinvar property. The variations in rigidity modulus and its temperature coefficient by the heat treatment, cold reduction rate and composition are very similar to those in Young’s modulus and its temperature coefficient. Over the range from about 100 to 650, in Vickers hardness of the alloys is varied in a complicated manner by the difference in heat treatment, cold reduction rate and alloy composition. The corrosion resistivity of Mn-Ni-Mo alloys is fairly good.

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Cu-1% Al alloys containing 0.5∼1.5% each of Ag, Pd, As and In were internally oxidized to study the double effects of solution and dispersion strengthening. These four elements are capable to form solid-solutions with Cu. Ag and Pd have lower absolute values for the free energy of oxide formation than Cu, while As and ln have greater values.
The following results were obtained.
(1) In both Cu-Ag-Al₂O₃ and Cu-Pd-Al₂O₃ alloys, double effects of solution strengthening by Ag or Pd addition and dispersion strengthening by Al₂O₃ particles were realized. Tensile strengths of 56 and 54 kg/mm² were obtained for Cu-0.5% Ag-4.5 vol% Al₂O₃ and Cu-0.5% Pd-4.5 vol% Al₂O₃ alloys, respectively, when internally oxidized for 50 hr at 850°C, while Cu-4.5 vol% Al₂O₃ showed the strength of 49 kg/mm².
(2) Double effects were not found in the alloys containing As or In whose absolute values for the free energy of oxide formation are higher than Cu.
(3) The time for internal oxidation to obtain a maximum mechanical strength was much longer than that to oxidize as for as the core part determined by metallographic observation, but exhibited a fairly good agreement with that needed for attaining the saturation of electrical conductivity.

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The solubililties of Fe₄N in iron alloys with cobalt, molybdenum or tungsten were studied using an improved internal friction technique. The solubility in the present work was determined by connecting the broken points of Q_max⁻¹ with the fall of aging temperatures. By adopting this method instead of the conventional method, it was possible to eliminate the effect of precipitate on the internal friction value and to determine the solubility for iron alloys having a complex Snoek peak.
The addition of cobalt, molybdenum or tungsten in alpha-iron renders an increasing effect for the solubility of Fe₄N and a decreasing effect for the heat of solution of Fe₄N. The solubility and the heat of solution of Fe₄N in various iron alloys are given by the following equations:
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In relation to the surface temperature the wear characteristics of cast iron rubbed against nickel and constantan in dry sliding on a pin-ring test rig in 10⁻⁴ mmHg were examined by measuring the temperature at actual contacting asperities, i.e., the flash temperature, and the average temperature of the sliding surface.
It is estimated that the flash temperature which is converted from the thermo-electromotive force developed between the sliding surfaces does not indicate the maximum temperature among numerous asperities contacting simultaneously or the temperature at each individual asperity, but represents the average temperature at asperities. The average temperature of the sliding surface is considered to be indicative of the initial temperature of asperities and/or the temperature of parts which suppot asperities.
The flash temperature is closely related to wear and the white hardened layer caused by melting of asperities on the sliding surface. When the average temperature of actual contacting asperities is about 300°C, the wear of cast iron is the largest and decreases beyond this temperature. In a state where all asperities contacting simultaneously come to the melting point, wear reaches the minimum and more than 70% of the sliding surface is covered with white hardened layers. The quantitative relation between wear and the maximum flash temperature, from which an experimental equation could be obtained, was recognized in a sliding condition where the white hardened layer occurs on the sliding surface. The flash temperature measurement by the thermo-electromotive force developed between the sliding surfaces must be an effective source to make clear the wear characteristics. The severe seizure due to softening of the sliding surface does not occur in cast iron, when the average temperature of the sliding surface is lower than 500°C.
At high sliding speeds where a large quantity of frictional heat generates, wear reaches the minimum in a state at which the temperature of actual contacting asperities approaches the melting point or a high temperature near to it and a sufficient strength is maintained on the parts supporting asperities. The average temperature of the sliding surface is considered to have a significant meaning as the value to judge the occurrence of seizure.

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Wear tests, measurements of the average temperature of the sliding surface and calculations of the temperature of asperities by using Jaeger’s equation were performed on 0.45% C carbon steel rubbed against 0.6% C carbon steel and stainless steel in dry sliding on a pin-ring test rig in air and in vacuo, from which the wear characteristics of 0.45% C carbon steel were discussed in relation to the surface temperature.
From the results obtained in this experiment and reported previously, it is concluded that wear of iron and steel reachs the maximum at the average temperature of about 300°C for asperities, and decreases beyond this temperature. Wear of carbon steel increases with seizure when the average temperature of the sliding surface exceeds about 200∼250°C. In a state where the temperature of actual contacting asperities approaches the melting point or a high temperature near it, at least above A₁ temperature, and the average temperature of the sliding surface is kept at comparatively low temperatures at which the parts supporting asperities do not begin to soften, wear reaches the minimum and the white hardened layers mostly occur on the sliding surface. In the case of occurrence of the white hardened layers, therefore, the cause for the decrease in wear may be attributed not to the high value of hardness of the white layer after sliding, but to the fact that a high temperature is attained only in the neibourhood of the interface of contacting asperities to produce rupture.
Oxidation of the sliding surface does not always reduce wear, and wear in vacuo, in which the macroscopic oxidation does not occur, is smaller than in air when the actual contacting asperities reach a high temperature and the average temperature of the sliding surface is comparatively low. In air, thick oxide layers reduce the average temperature of the sliding surface and prevent seizure in a condition where this temperature exceeds 200∼250°C in vacuo.

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Following the preceding work, the present work was made in order to find another new method for the measurement of oxygen diffusivity in liquid metal. Using the electrochemical cell, Ar(1% O₂), O(in liquid silver)/ZrO₂(+CaO)/Ar(1% O₂),the diffusivity of oxygen in liquid silver was determined by the potentiostatic titration method and the e.m.f. method newly developed.
The potentiostatic titration experiment was undertaken by the same procedure as in the previous work except some improvements in the experimental technique. Another e.m.f. experiment was undertaken as follows; potentiostatic titration was continued until a steady state was obtained and then the change of e.m.f. was measured after electric current was cut off. The diffusivity of oxygen was determined from the change of e.m.f. according to the following relation:
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The results obtained by the above two different methods were in good agreement with the previous result. However the activation energy determined by the e.m.f. method was a little larger than that by the potentiostatic titration method. These experimental results showed that the oxygen diffusivity in liquid metal could accurately be determined by these electrochemical methods. And these experimental methods may be recommended in particular for the metal which has a strong affinity with oxygen.

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