Thermomigration of hydrogen and deuterium in vanadium, its alloys (V–Ti, V–Cr, V–Fe and V–Mo), niobium and tantalum has been measured by a steady state method. Both isotopes migrate toward the colder end. The observed heat of transport, Q^*, in pure metals increases in order of vanadium, niobium and tantalum, and is significantly smaller for hydrogen than for deuterium. The addition of Ti and Cr increases Q^* in vanadium, but Fe and Mo do not much affect Q^*. A model of trapping of hydrogen (deuterium) by substitutional elements is applied to explain the increase in Q^* for vanadium alloys.

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Crack propagation of high strength steels with the tensile strength of 1500 or 2000 MPa was investigated at room temperature in an oxygen-doped gaseous hydrogen atmosphere. The doped oxygen gas suppressed the crack propagation in the range of stress intensity factor K below a critical value, at which a hydrogen induced crack began to propagate in a steady state under a load relaxation test i.e. a rising K test. The steady crack propagation rate was hardly affected by the content of doped oxygen gas. The critical value of K was dependent on both hydrogen and oxygen pressures and not determined only by the oxygen concentration in hydrogen. The effect of oxygen was explained by the assumption that oxygen gas decreased the number of absorption or adsorption sites of hydrogen on the crack tip surface and consequently the permeation of hydrogen flowing into a specimens decreased with increasing oxygen pressure.

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Interdiffusion coefficients of the quasi-binary Al₂O₃–Mn₃O₄ system in air have been studied at temperatures from 1573 to 1773 K. The diffusion couple consisted of a single crystal Al₂O₃ whose (012) plane of trigonal lattice was placed in contact with a sintered polycrystalline Mn₃O₄. The Pt-markers were embedded into the initial contact interface of the diffusion couple. The master curves of concentration penetrations in the direction of diffusion were obtained at each experimental temperature. Interdiffusion coefficients were calculated by the Matano-Boltzmann method. The results can be represented by:
\ ildeD=2.02×10⁻¹¹exp(−138000J⁄RT)m²s⁻¹ at 8.8 at% Al
\ ildeD=1.38×10⁻⁸exp(−185000J⁄RT)m²s⁻¹ at 25.2 at% Al.
The reaction mechanism in this system and the crystal structure of diffusion layer were discussed. On the Mn₃O₄-side, the spinel phase of diffusion layers grew epitaxially to the ⟨111⟩ direction. On the Al₂O₃ side, the polycrystalline spinel grew up.

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The liquid Cu–S–O system was studied thermodynamically by measurement of emf using a zirconia solid electrolyte under two constant SO₂ partial pressures, p_SO2/P°=0.005 and 0.01, at 1473 and 1573 K.The galvanic cell used was
Pt, Ni–NiO/ZrO+MgO/Cu–S–O(1)Cr₂O₃, Pt.
With increasing oxygen content in the liquid copper, the sulfur content decreased at both temperatures under both constant SO₂ partial pressures.
The activity of oxygen in the liquid Cu–S–O system at a low oxygen concentration range deviated negative from linearity, because of the effect of sulfur on the oxygen activity. The activity coefficients of oxygen at an infinite dilution in the Cu–O binary system and the first order interaction parameter, ε₀^s were calculated between 1473 and 1573 K.

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Dense plates of pentlandite, Fe_4.5Ni_4.5S₈, were oxidized at 783, 823 and 863 K in a mixed O₂–N₂, gas stream. Partial pressure of O₂ gas in the mixed gas was 20 kPa. Iron was preferentially oxidized, and a duplex oxide was formed on the sample surface: The outer and inner oxides were Fe₂O₃ and Fe₃O₄, respectively. A small amount of nickel was contained in Fe₃O₄. A very small amount of SO₂ gas was evolved in the initial 100 s of oxidation, and no SO₂ gas was detected thereafter. The analysis of elements using EPMA in the inner sulfide revealed, on the other hand, that sulfur was oxidized slowly during the oxidation for 72 ks. The thickness of Fe₃O₄ layer increased rapidly at the initial stage of oxidation, and then both layers of Fe₃O₄ and Fe₂O₃ grew in accordance with the parabolic rate law. The activation energies for the growth of Fe₃O₄ and Fe₂O₃ layers were 170 and 160 kJ·mol⁻¹, respectively.

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Activity measurements of Na₂O in the system Na₂O–Fe₂O₃ have been made by EMF method using sodium beta-alumina as a solid electrolyte between 850 and 1500 K. The cell employed in this study was written as;
(Remark: Graphics omitted.)
From the determined values of Na₂O activity, the values of the standard free energy change for the formation of Na₃Fe₅O₉ and Na₂Fe₅O₉ from pure solid Na₂O and Fe₂O₃ were also calculated as;
ΔG°(Na₃Fe₅O₉)⁄kJ·mol⁻¹=−(248.6±1.1)−(2.447±1.188)×10⁻³T⁄K (<1405 K),
ΔG°(Na₂Fe₂O₄)⁄kJ·mol⁻¹=−(160.2±2.5)−(3.909±1.245)×10⁻³T⁄K (<1047 K),
=−(152.7±2.4)−(1.332±1.227)×10⁻³T⁄K (1047<T<1278 K),
and
=−(147.3±2.9)−(13.37±1.268)×10⁻³T⁄K (1278<T<1405 K).

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The effect of die angles has been investigated by means of metallographic observation and visioplasticity analysis in order to optimize the design of the hot extrusion die. In addition, the distribution of pressure acting on the surface of the die block has been evaluated through the analysis of the output of high-temperature strain gage attached to the external surface of the die block. The flat die of 90° die semi-angle brings about the lowest extrusion pressure of all dies. For the 90° die semi-angle, the flow speed under the same ram load is larger than that for any other semi-angles, and the best extrudability is attained. For the die semi-angle smaller than 90°, the metal flow becomes more parallel with the die surface and is suppressed more easily by the sliding friction with the die surface, the flow speed decreases under the same ram load and the internal sliding friction also results in lower extrudability. The highest pressure acts on the bearing part for every die semi-angle. As the die semi-angle becomes larger, the pressure acting on the bearing tends to decrease. For the 90° die, the pressure becomes about 60% of that for the 45 die. A comprehensive examination of the optimum die semi-angle shows clearly that the 90° die is most suitable for hot extrusion in terms of extrudability and die performance.

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The correlation between the mechanical property change and the AE signal produced during the 3-point bending test was investigated for the carbon fiber reinforced aluminum. The results of the AE measurement reflect the change of strength by heat-treatment and SEM fractography. The change of the fracture mechanism due to the thermal history of the specimen can be detected by the frequency spectrum analysis of the AE signal. The slight change in the bonding between carbon fiber and aluminum matrix which is not observable with SEM can be detected by the analysis of the AE frequency spectrum diagrams.

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Detachment of secondary dendrite arms has been observed in succinonitrile-camphor alloys under the microscope. The dendrites have been grown under a positive temperature gradient (columnar growth). After the tip has reached the thermocouple the displacement of the specimen was inversed and the remelting behaviour observed. It is found that detachment of arms is more frequent in concentrated alloys, when the growth rate is high and the melting rate low.

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