A consideration of the dynamic aspects of materials of the relaxation type has been made by analyzing the 3-lumped parameter vibration model based on S.L.S. Regarding its transient response, the asymmetrical damped free oscillations, sometimes observed in the high damping relaxation system such as Al–Zn eutectoid alloys and Bi films, can be explained from the relative geometrical configurations of the characteristic roots (poles) and the zero on the s(Laplace operator)-plane; for large Δ_K(relaxation strength) of about 0.5, the asymmetry is pronounced, while for small Δ_K(\simeq10⁻³), it is scarecely appreciable. Even when the asymmetry is pronounced, the method for evaluating the damping capacity is confirmed to be the same as the usual one based on the relative decrement in vibrational amplitudes. In the high Δ_K system, the estimation of Q⁻¹ using the impulse response method is more convenient because occurs no asymmetry on the transient response curve. On the other hand, as for the resonant response, the resonant amplitude and frequency vary with the viscous coefficient ratio (ζ) which is a function of temperature. Especially, the value of ζ for the resonant curve, whose peak is the lowest, is equal to a half of Δ_K.

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The pressure-composition-temperature relations for niobium selenides NbSe_x were determined by annealing the sample under controlled selenium vapor pressure in the composition range x=1.48−2.00. There exist five phases; Nb₂Se₃, 2H(a), 3R, 2H(β) and 4H . The 2H(a) and 3R phase are known stable over a wide range of nonstoichimetric composition; the 2H(β) and 4H phases have an extremely narrow range at composition x=2.00. The defect structures of 2H(a) and 3R phases were analyzed using statistical thermodynamics.

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The dependence of electrical properties—resistivity and superconducting transition temperature—on changes in composition and structure was studied for niobium selenides NbSe_x. In the 4H and 2H(β) phases, the maximum superconducting transition temperatures are 6.61 and 7.60 K, respectively, at the stoichiometric composition and decrease as the composition deviates from stoichiometry. In the 3R and 2H(a) phases, no superconducting transition is observed down to 1.6 K probably due to the large concentration of defects. In the Nb₂Se₃ phase, the maximum superconducting transition temperature is 2.47 K at the stoichiometric composition and decrease with increasing deviation from stoichiometry.

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Single crystals of iron with the [110] and [410] axes were fatigued in push-pull at constant total strain amplitudes in the range between 0.1 and 2%. When the strain amplitude was smaller than 0.5%, the cyclic hardening of the [410] crystal was similar to that of the [110] crystal. Clusters of edge dislocation dipoles and loops were developed parallel to the {112} slip plane, which suggests the activation of single slip locally. When the strain amplitude is larger than 0.5%, the cyclic hardening of the [410] crystal was much larger than that of the [110] crystal. Cell walls lie along symmetry planes with respect to the slip planes, which suggests multiple slip. Striation patterns on the fracture surfaces appeared parallel to the intersection between operative {112} slip planes in both crystals. When a crack was forced to propagate to perpendicular to the slip vectors, in the [\bar110] direction on the (110) plane, it propagated in the ⟨332⟩ directions with a deviation of 40 degrees from the [\bar110] direction.

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A metastable phase in a quenched β₁ Cu–14.2Al–4.3Ni (in wt%) alloy has been investigated by means of electron diffraction and electron microscopy. The structure of the metastable phase has been analyzed by a model proposed by Takezawa and Sato for a Cu–Zn alloy, by taking into account the effect of ordering for the present alloy. It has been found that the transformation between the β₁ matrix phase and the metastable 2H type phase is reversible and diffusionless in nature. Furthermore, clear evidence has been found that the 2H type phase and the so-called “mottled structure” are present even in the martensitic phase. This is a strong indication that the 2H type phase is not a premartensitic phase but a metastable phase which competes with the subsequent martensitic phase.

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Amorphous alloys of a new type have been found in alloy systems of chromium-transition metals-carbon, such as Cr–Fe–C, Cr–Co–C, Cr–Ni–C, Cr–Nb–C, Cr–Mo–C and Cr–Ta–C, by a rapid quenching technique. Specimens were produced in the form of a continuous ribbon of about 1 mm width and 0.03 mm thickness by using a modified single roller quenching apparatus designed by the present authors. The carbon content in these amorphous alloys is limited to the range between about 15 and 23 at% and the alloy compositions are in the ranges of 9∼59 at% Fe, 15∼57 at% Co, 27∼51 at% Ni, 11∼17 at% Nb, 7∼23 at% Mo and 7∼13 at% Ta, respectively. These new alloys are expected as a high-hardness material with high thermal stability of structure. Vickers hardness number decreases by the addition of Fe, Co and Ni, while the value increases with an increase in Nb, Mo and Ta contents. Also, the amorphous structure of these alloys is thermally more stable as compared with the other amorphous alloys of metal-metalloid system reported so far. The maximum hardness and crystallization temperature are about 1400 DPN and about 1030 K, respectively. The effectiveness of alloying elements on increasing hardness and crystallization temperature decreases in the order of Nb, Ta, Mo, Fe, Co and Ni.

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Following a brief review of characteristic features of mechanical properties in nickel-based intermetallic compounds with the L1₂ structure, in-situ observations of deformation process of Ni₃Ga single crystals are described. Based on these results, the anomalous, inverse temperature dependence of the macroscopic yield stress of the above compounds is concluded to be ascribable to an exhaustion hardening mechanism of {111} slip, where source dislocations are self-trapped by thermally activated locking of screw segments due to the Kear-Wilsdorf mechanism. A model is proposed for the process of macroscopic yielding.

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Iron test pieces were diffusion-annealed at 973∼1223 K for 32.4∼1584 ks in an evacuated quartz ampoule containing powdered (100∼200 mesh) 50 wt%Sb–Fe alloy, consisting of α and ε phases, as an Sb vapor source. After annealing, cross-sections of the test pieces were analysed with an EPMA in order to determine the penetration of Sb.
Each penetration curve was analysed by the Matano-Boltzman method to calculate the interdiffusion coefficients, \ ildeD. The activation energies for interdiffusion (\ ildeQ) were also obtained.
The surface concentration of Sb in the test piece (α_max) at lower temperatures coincided approximately with the solubility limit reported in the phase diagram of the Fe–Sb system, while a significant deviation in solubility limit was found at higher temperatures. Fine alumina markers placed on the test pieces prior to diffusion remained on the surface after annealing, so that it is considered that Sb atoms diffuse predominantly into the α phase of this system. Each penetration curve except for 1223 K was similar to an error function curve for a particular \ ildeD value. The value of \ ildeD showed a relatively small dependence upon the Sb concentration at each temperature. There was a gap in the Arrhenius plot of \ ildeD owing to magnetic transformation. The activation energies for interdiffusion (\ ildeQ) obtained from the data at higher temperatures decreased with increasing Sb concentration from 249 kJ/mol for 1 at%Sb to 220 kJ/mol for 4 at%Sb. The activation energy for the impurity diffusion of Sb in iron (Q_Sb^*) was evaluated to be about 262 kJ/mol.

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