The ultrasonic velocity in molten bismuth, aluminum, silver and copper has been measured by using a pulse-echo method at 10 MHz in the temperature range from their melting points to the temperatures about 250 K higher than the melting point. The relation between the velocity and the temperature can be represented by a straight line having a negative temperature coefficient for molten Al, Ag and Cu. But the temperature dependence of molten Bi is different from the others, i.e., it remains almost constant over the range of 100 K above the melting point and then becomes negative with increasing temperature.
The adiabatic and isothermal compressibilities were calculated at the melting points from the experimental results combining with the other thermodynamic data and compared with theoretical values calculated by simple models. It was found that the values calculated by Ascarelli’s model agreed well with the experimental values except Ag and Cu, while the hard sphere model did not yield satisfactory results. From this fact, it may be concluded that the contribution of free electron gas can not be neglected for the explanation of the compressibility of these molten metals.

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A neutron-irradiated copper crystal (φ=1×10²² n·m⁻², E>0.1 MeV) has been elongated at room temperature to investigate pre- and post-yield deformation and work-hardening in stage I deformation in connection with the formation of primary and secondary slip bands using an etch-pit technique. Main results are as follows:
(1) Individual deformation stages of a stress (τ)-strain(γ) curve just corresponds with individual stages of a N_p-γ curve, where N_p is the number of the primary slip traces.
(2) The primary slip begins to appear at the multiplication stress (τ_m) much less than the upper yield stress (τ_uy), and τ_m is about 70% of τ_uy.
(3) The spacing of the primary slip traces and the shear displacement in them decrease in yield deformation with increasing strain, but they are constant in stage I independently of strain.
(4) The mobility of edge dislocations is surely larger than that of screw ones.
(5) The secondary slip begins to grow from a definite side of the clusters of the primary slip traces towards undeformed matrices.
(6) There is a surface effect in the formation of the secondary slip bands.
From these results, the mechanism of pre- and post-yield deformation, the work-hardening in stage I deformation and heterogeneous formation of the secondary slip bands are discussed.

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Intrinsic diffusion coefficients, D_Cu and D_Ni, in the concentration range from 25 to 80 at% Cu at 1273 K have been determined by measuring the shifts of multiple markers of chromium oxide particles (about 1 \micron diameter) which had been embedded before diffusion in the nickel side of a semi-infinite couple consisting of pure copper and nickel in a way that the markers array has made an angle of π⁄4 rad with the diffusion direction. By the present method, it is possible to provide more detailed concentration dependence of the intrinsic diffusion coefficients than those by the usual methods. The intrinsic diffusion coefficients determined by the present work are in agreement with the results by Heumann and Grundhoff, although the present values including the interdiffusion coefficient are apparently high in the copper-rich region because of the formation of large Kirkendall voids.

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Thermodynamic behaviour of sulphur in dilute solution range in the liquid binary lead-silver alloys has been studied by the H₂S–H₂ gas equilibrium method using a closed-circuit recirculation technique. The amount of sulphur dissolved in the binary lead-silver alloy of different compositions equilibrated with H₂S–H₂ gas mixture of definite composition and at definite temperatures has been determined by the spectrophotometric method. Data obtained on the solubility of sulphur have been used to calculate the free energy, the enthalpy and the entropy of solution of sulphur. Empirical results obtained in the present investigation have been analysed in the light of existing theoretical solution models.

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The hardening mechanism of Ni maraging steels on aging and on repeated strain aging has been investigated by means of specific heat, electrical resistivity and hardness measurements, etc. On aging in the temperature range from 600 to 800 K, Mo rich zones are formed prior to the precipitation of Ni₃Mo, leading to the pronounced hardening in Ni maraging steels. These zones are considered to transform to Ni₃Mo by the in situ type process in the later aging stage. At the aging temperature below 720 K, however, this transformation does not proceed in the hardening stage but occurs in the over aging stage.
Repetition of low temperature aging and cold working (repeated strain aging) leads to the acceleration of formation of Mo rich zones, resulting in a rapid increase in tensile strength. For example, the tensile strength of a specimen with the 10 cycles repetition of the 748 K–120 s aging and 5% cold working reaches 1700 MPa, which exceeds the highest tensile strength of 1500 MPa attained by the 748 K–36 ks aging. This suggests that Mo rich zones are fromed on dislocations, and that the dislocations released (or newly generated) by the cold working on the above treatment can again supply the nucleation sites for the next formation of Mo rich zones.

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