The electrical resistivity and magnetization of Ni-base alloys containing Zn up to 25 at% were respectively measured between 4.2 and 1000 K and at 77 K. With increasing Zn content, the magnetic contribution to the resistivity slightly increases and has a broad maximum at 8–16 at% Zn, notwithstanding the linear decrease of the magnetization or Curie temperature. This anomalous composition dependence of the magnetic resistivity in ferromagnetic Ni–Zn alloys is explained as a result of the coexistence of scattering processes of spin disorder and s−d transition, as previously reported in the Ni–Cu and Ni–Co alloys. It is pointed out that the hole-carrier, which is observed in the ordinary Hall effect or the resistivity due to the phonon scattering, behaves as the probability of interband s−d transition in the magnetic resistivity.

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Effect of Si on the formation of Mn–C dipoles in low carbon steels has been investigated. The changes in electrical resistivity were measured at 77 and 273 K during isothermal ageing for quenched Fe–Si–Mn–C alloys containing various Si contents (0–0.8 at%). The deviation from Matthiessen’s Rule (DMR) was given by the difference between the electrical resistivities at 77 and 273 K. The DMR during ageing increased in the steels containing Si when quenched from the temperature between 673 and 973 K. Even in the Si-free steel the DMR during ageing increased when quenched from 673 and 773 K. These results showed that Mn–C dipoles retained after quenching were decomposed during ageing and single Mn atoms in solution increased. The amount of Mn–C dipoles or their binding energy increased with the increase of Si content up to 0.4 at%. It was suggested that the potential energy at the Fe–Mn, Fe–Fe and Fe–Si interstitial sites increased in that order by the addition of Si to the Fe–Mn–C system. Thus C atoms may be trapped at the Fe–Mn interstitial sites to form Mn–C dipoles. The amount and the binding energy of the Mn–C dipoles became saturated at Si contents more than 0.4 at%. The formation of dipoles at the Fe–Mn sites was considered to be restrained by repulsive interaction with excessive Si atoms.

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Measurements of the electrical conductivity, magnetic susceptibility and thermoelectric power of liquid Tl–TlInTe₂ and In–TlInTe₂ systems have been carried out over wide temperature and composition ranges. The composition dependence of the electronic properties investigated exhibits that there is a rapid increase in both electrical conductivity and paramagnetic contribution in the metal-rich region above 66.7 mol% of Tl and In corresponding to the stoichiometric compositions of Tl₃InTe₂ and TlIn₃Te₂. In addition, a change in the sign of the thermoelectric power occurs at these compositions in both systems. The observed electronic properties are discussed in terms of the delocalized model of electrons, i.e., the diffusive transport theory and the model which includes the metallic approximation. The results show that the nonmetallic contribution is pronounced in the Tl–TlInTe₂ system compared with the In–TlInTe₂ system. Consequently, the anomalous behavior of the electronic properties observed around 66.7 mol% of Tl and In in the present systems is considered to be caused by the nonmetallic nature of Tl(I)–Te bonds.

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Most of the conventional formulae used for evaluation of the mean grain size of the actual polycrystalline materials were derived on the assumption of a perfectly uniform grain structure. This means that the distribution of the grain size was left out of consideration. Since the assumption has little possibility of being held true in actual structures, a new and significant formula for the mean grain diameter D_mean has been derived on the assumptions of the log-normal distribution of the grain diameters and the grain shape of the β-tetrakaidecahedron [Fig. 1(c) in text]. The resultant formula is as follows: D_mean=κL_A²⁄L_L, where L_L and L_A are the mean grain sizes measured on the planar section by the linear intercept method (Heyn’s method) and the planimetric method (Jeffries’ method), respectively. The symbol of κ is a correction factor for the conversion of grain shape from the sphere to the β-tetrakaidecahedron, which is estimated to be 0.980 in the present study.

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The effect of deformation-induced martensite on the tensile behavior of metastable austenitic stainless steel has been investigated on a AISI Type 301 stainless steel containing a small amount of copper using the X-ray diffraction technique and transmission electron microscopy. The formation of martensite during tensile deformation increases the accumulation of dislocations in the austenitic phase, which leads to the enhanced work-hardening rate of this type of steel. The linear relationship between the flow stress and the square root of dislocation density in the austenitic phase can be obtained even when martensitic transformation occurs during tensile deformation as well as under the condition of single-phase deformation above the Md temperature. In conclusion, deformation-induced martensites behave not only as hardening bodies by themselves as usually considered, but also as the accelerator of accumulation of dislocations in the austenitic phase. This is because excess dislocations are introduced to accomodate the volume expansion through martensitic transformation and the martensites act as obstacles for slip which results in the increase of dislocation density in the austenitic phase.

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Low frequency internal friction of two elinvar-type alloys was measured in a torsion pendulum. The temperature coefficient of the shear modulus near room temperature was evaluated from the vibrational frequency which was simultaneously measured with internal friction. The creep behaviour of these alloys is predicted by analysing the high temperature internal friction which increases exponentially with temperature.

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It has been considered that products with particular crystal structures, such as unidirectionally solidified columnar grains, a single crystal and an in-situ composite eutectic structure, can be manufactured with an upward continuous casting process. In this work, after surveying various upward continuous casting processes reported in the literature, a moldless one was selected. An apparatus for this process was constructed, and trial experiments with Al were performed. The producing conditions of aluminum rods by the apparatus were investigated. The temperature distribution along the cast strand was measured by a thermocouple attached to the tip of the dummy bar. The structure and the surface conditions of the cast strands were examined. The temperature measurement showed that the solidification front of the cast strand located 10∼25 mm above the surface of the molten metal. The growth direction of the columnar grain of the cast strand showed that the configuration of the solidification front of the cast strand was flat or slightly convex. The diameter of the cast strand was determined by the temperature of the molten metal, the intensity of the cooling, and the speed of the upward withdrawing. Cast strands with plus tapers (growing bigger) were obtained at lower temperatures, more intensities and lower speeds. The structure of the dummy bar affected that of the cast strand. The cast strand was composed of columnar crystals solidified completely unidirectionally. Surface conditions of the cast strand were better at lower rotation speeds of cast strand, higher temperatures of molten metal and higher speeds of upward withdrawing.

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In order to clarify the effect of die materials on the isothermal forging properties such as forging load, die filling and heat power consumption, forging tests of nickel-base superalloy Mod.IN-100 from a cylindrical preform to a disk shape with boss and rim have been performed. The die materials used are two refractory alloys, TZM and W–2ThO₂, ceramic SIALON and nickel-base cast superalloy IN-100. Forging with refractory alloy dies are done in a chamber filled with inert gas (Ar) or vacuumized to prevent the oxidation of die. On the other hand, with ceramic or cast superalloy dies, forging can be done in air without the use of the chamber. In these tests, the HIP’ed and extruded preform from Mod.IN-100 powder is used as a test material, and a glass powder suspended in water is used as a lubricant. By using the optimum size preform, isothermal forging of Mod.IN-100 can be carried out successfully in all cases. There are no differences in load and material flow in forgings, regardless of the die material selected. From the practical point of view, however, the forging method with ceramic or cast superalloy dies in air has been experimentally proved to be more appropriate than that with refractory alloy dies in inert gas or vacuum.

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Superplasticity in a recrystallized Ni₃Al polycrystal doped with boron was investigated. Superplastic flow with a maximum elongation of 160% was observed under the condition of an ultra fine grain size (1.6 μm) at a low initial strain rate (≤1.04×10⁻⁴s⁻¹) and 973 K. A low flow stress and a high strain-rate sensitivity index were attained under these conditions.
The occurrence of a dynamic recrystallization (DR) was verified by a transmission electron microscope (TEM), and DR was believed to be an important mechanism in superplastic deformation as associated with a reduced cavitation. This limited cavitation was explained by considering that DR relieves stress concentrations arising from grain boundary sliding and dislocation piling-up at grain boundaries. In addition, DR played another important role in suppressing apparent grain growth during superplastic deformation.

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