The impurity diffusion coefficient of tin in γ-iron has been determined by the serial sectioning method with the radioactive tracer ¹¹³Sn in the temperature range between 1197 and 1653 K. The temperature dependence of the diffusion coefficient shows the linear Arrhenius relationship, expressed by
D=(0.845_−0.119^+0.141)×10⁻⁴exp[−(261.7±1.8)kJmol⁻¹⁄RT]m²s⁻¹.
The magnitudes of both the frequency factor and the activation energy can be regarded as normal. The anomalously low values obtained by the previous workers appear to be due to enhanced diffusion through short circuiting paths such as grain boundaries and dislocations and by impurities contained in their iron specimens.

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The temperature dependence of the flow strength for two austenitic stainless steels (SUS 304L and 304LN) and one commercially pure Ti (JIS class 2) has been investigated at the temperature range between 4.2 and 77 K. All materials studied exhibited an anomaly in the low temperature dependence of flow strength. 304L steel showed a peak at 24 K on the flow strength versus temperature curve, and 304LN steel showed two peaks at 7 and 40 K. Commercially pure titanium also showed a maximum at 14 K. Magnetic measurements for austenitic stainless steels indicated that the anomalies were not due to the magnetic transition. The anomalies are considered to be due to the dislocation inertial effect on the thermally activation process.

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The effect of strain rate on the yield stress of an Al-11.1 mol%Li alloy containing δ′-precipitates has been investigated at temperatures between 77 and 523 K and over the strain rate range from 1.77×10⁻⁴ s⁻¹ to 1.77×10⁻² s⁻¹. At testing temperatures below 373 K, the yield stress is almost independent of strain rate at any aging stage. At testing temperatures above 373 K, the yield stress increases linearly with the logarithm of strain rate, and its strain rate dependence increases with increasing testing temperature. The yield stresses of under-aged alloy at temperatures between 373 and 473 K at high strain rates are greater than the yield stress at 77 K. For the alloy under-aged or aged nearly to its peak strength, the temperature range within which the positive temperature dependence of yield stress appears expands to the higher temperature side with increasing strain rate. The strain rate dependence of the yield stress is slightly negative at this aging stage. Within this temperature range, dislocations move in pairs cutting δ′-Ll₂ ordered particles. The yield stress of the over-aged alloy decreases monotonically with decreasing strain rate and with increasing testing temperature above 373 K. The modulus normalized yield stress is nearly constant at testing temperatures below 373 K at any strain rate investigated. In the over-aged alloy, dislocations by-pass the precipitates at any temperature and strain rate.

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The stress corrosion cracking (SCC) initiation behavior under a sustained load with small vibratory loads superimposed has been investigated on a high-strength low-alloy steel AISI 4135 sensitive to hydrogen embrittlement (HE) type SCC immersed in 3.5% NaCl solution at both the free corrosion potential and the cathodically charged potential at E=−1.0 V (SCE). At the free corrosion potential, the time to crack initiation with small vibratory stresses superimposed is shorter than that of static SCC with lower 600 ks strength than σ_SCC for static SCC. At Δσ≤74 MPa, however, the effects of superimposed stresses on 600 ks strength are negligible with the same value as σ_SCC. At σ_max>σ_SCC, SCC cracks are initiated at the corrosion pits formed on specimen surfaces. At σ_max<σ_SCC and Δσ>74 MPa, however, superimposed vibratory stresses promote stress-assisted crack-like dissolution preceded by corrosion pits; dynamic SCC cracks are initiated at the bottom of crack-like defects, resulting in the lower dynamic SCC strength. K_ISCC^*, which is obtained by assuming the corrosion pits and the crack-like defects to be sharp cracks, is roughly equivalent to K_ISCC obtained by long, sharp crack specimens. When the cathodic potential is applied to specimens, the effects of superimposed small vibratory stresses on the 600 ks strength are negligible, because the metal dissolution reaction is inhibited. In such cases SCC cracks are initiated at the interior of specimens where the triaxial stress is maximum.

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A systematic evaluation has been made on the magnitude of the positive temperature dependence of strength in Ni₃Al as affected by ternary additions of B-subgroup elements. The rate of change in activation energy to provide the mechanical anomaly per one atomic per cent of the solute, dU⁄dc, is determined for a variety of the ternary additions. It is shown that the larger the valence difference between the solute element and aluminum, ΔZ, the larger the dU⁄dc. Also found is that the larger the rate of lattice parameter change in the compound per one atomic percent of the solute, da⁄dc, the larger the dU⁄dC. These are well interpreted in terms of the phase stability concept to determine the relative magnitude of the mechanical anomaly in the L1₂ compounds, in which e⁄a ratio of the compound and the atomic radius ratio of the components, R_B⁄R_A, are the key factors to alter the stability of the phase against other geometrically close packed phases and thereby control the occurrence and the magnitude of the mechanical anomaly. The effect of ternary additions of B-subgroup elements on the rate of solid solution hardening per one atomic percent of the solute, dσ⁄dc is also discussed. There seems to be a linear correlation between the dσ⁄dc and the da⁄dc implying that the atomic size effect would play a major role in the solid solution hardening in Ni₃Al.

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A systematic investigation is carried out on the temperature dependence of strength in ternary Ni₃Al compounds with additions of transition metal elements. The rate of solid solution hardening per one atomic percent of the solute, dσ⁄dc, is determined for each of the ternary addition using the compressive flow stress measured at liquid nitrogen temperature. It is found that dσd⁄dc can not be simply correlated with the rate of lattice parameter change, da⁄dc, although a linear correlation has been found for the addition of B-subgroup elements. The rate of change in activation energy to provide the anomalous positive temperature dependence of strength per one atomic percent of the solute, dU⁄dc, is then evaluated. Together with the results for the addition of B-subgroup elements, the apparent valence is assigned for each transition metal element by an analogy utilizing equi-valence contour determined for B-subgroup elements. Then it becomes possible to discuss the relative magnitude of the mechanical anomaly in Ni₃Al in terms of the phase stability concept of L1₂ phase, in which e⁄a ratio as well as the atomic radius ratio of the compound, R_B⁄R_A, as affected by ternary addition is an important parameter to alter the stability of the phase against other geometrically close packed phases.

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The effect of cooling conditions on the structure of the momentum boundary layer has been studied under circumstances characteristic of the single roller rapid quenching technique.
In spite of some recent results, the present computations, which take the heat and momentum transport and the temperature dependence of viscosity into account, suggest a more effective momentum transport and a thicker ribbon for better cooling conditions, supporting former expectations based on the pure heat transport treatment. However, it is also indicated that the solidification controlled ribbon formation can be excluded.

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The sintering behavior of prealloyed powder of Ni-base superalloy IN-100 was investigated by studying the solidification process of melted IN-100 powder through dilatometry, microstructural observations, DTA and EPMA.
Rapid densification of powder compacts occurred above 1513 K, while the sintering rate was very slow below 1493 K. This result suggested that the mechanism of sintering changed in the temperature range of 1493–1513 K. DTA during the sintering process of IN-100 powder compacts and during the solidification process of melted IN-100 powder detected five endothermic and five exothermic reactions, respectively. Microstructural observations revealed that three reactions (in the highest two temperature regions and the lowest temperature region) among the five reactions detected during the sintering process might be equivalent to those during the solidification process, that is, complete melting, γ-γ′ eutectic and γ′ solvus, respectively. The microstructures in the two intermediate temperature regions during sintering (1498–1523 and 1523–1548 K), where the mechanism of sintering changed, were greatly different from those during the solidification process, but approached those found during the solidification process after holding in the temperature regions for extended time. This result showed that the two reactions might correspond to non-equilibrium incipient melting which resulted from relatively rapid cooling from a melt in the powder production process (vacuum atomization).

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In order to clarify the mechanism of the formation of spheroidal and compacted/vermicular graphite in cast iron, two kinds of experiment were performed using molten iron treated with rare earth metal (REM) which has a less fading effect than Mg. At first, the interfacial energies between REM-treated molten iron and specific planes of graphite crystal were measured by the sessile drop technique. Next, Ni–C alloy sticks with spheroidal or flaky graphite were immersed into the REM-treated molten iron, and then the morphologies of graphite grown from the graphite of the stick into the molten iron were observed.
From these experiments, the following conclusion is drawn. The interfacial energy between the molten iron and the basal plane of graphite was almost independent of the residual Ce content, while the energy between the molten iron and the prism plane of graphite increased with increasing Ce content in the same way as in the case of Mg-treatment.
When the Ce content is low, the interfacial free energy ratio of single crystal is lower than that of polycrystal, and consequently the single crystal (flaky graphite) becomes more stable. When the Ce content is high, the ratio of polycrystal is lower than that of single crystal, and the polycrystal (spheroidal grahite) becomes more stable. When the Ce content is moderate, the ratios of both crystals are almost equal, and CV graphite is formed.
Therefore, the morphology of graphite grown into the molten iron is dependent on the interfacial energy between the molten iron and the specific plane of graphite, whether the graphite substrate is spheroidal or flaky.

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