Diffusion coefficients of ⁶⁰Co in single crystal α-Ti have been measured over the temperature range from 871 K to 1135 K. It has been confirmed that cobalt exhibits extremely fast diffusion about five orders of magnitude faster than the self-diffusion in α-Ti. The temperature dependence of the ⁶⁰Co diffusivities parallel and perpendicular to the c axis is expressed as
D_⁄⁄=1.9×10⁻⁶exp{−(114.1±0.9)kJ·mol⁻¹⁄RT}m²s⁻¹,
D_⊥=3.2×10⁻⁶exp{−(126.1±1.2)kJ·mol⁻¹⁄RT}m²s⁻¹.
It is suggested that some interstitial-type mechanism is operative in the Co diffusion in α-Ti.

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This paper reports the first finding that X-ray powder diffraction can detect superlattice reflections from the metal hydride. A hydrogen-ordered structure of Ta₂H has been studied on powdered specimens by means of a conventional X-ray diffractometer equipped with a monochromator between the sample and the detector. The use of the monochromator gives an excellent signal to background ratio in the diffraction pattern and enables us to observe weak superlattice reflections which have been missed so far. The obtained powder pattern can be indexed consistently with the superstructure reported by neutron diffraction work. Quantitative intensity measurements show that these superlattice reflections come from a systematic metal atom displacement induced by the ordered hydrogen arrangement, and the displacement has been estimated at 6.0×10⁻³ nm.

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The fatigue behavior of monocrystalline Cu–Al–Ni shape memory alloys have been investigated by uniaxial fatigue tests under various deformation modes. Fatigue life, N_f, was found to depend on the deformation modes and to be long in the order of elastic deformation, reorientation of martensites and transformation pseudoelasticity, indicating that interphase boundaries have a most deleterious effect on N_f. Stress dependence of N_f was observed in all the deformation modes, but strain dependence was not in transformation pseudoelasticity, indicating that the principal factor controlling N_f was stress. No orientation and strain rate dependences were observed. These results were compared with those previously reported on polycrystalline Cu–Al–Ni alloys. Effect of grain boundaries was found to depend on the deformation modes within grains and the strain allowed for a certain N_f for single crystals was found to be larger than that for polycrystals.

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Effects of addition of 0.1–0.5 mass% of Ti, 0.3 mass% of Co, Ni, Fe, Cd, Zn, Al, In, Mn, Cr or Si on the grain boundary reaction and the intragranular precipitation of γ′ phase in a Cu-2 mass%Be alloy on aging at 523 K after quenching from 1093 K were investigated by the quantitative metallographic method.
It was ascertained that In, Cd, Ni, Fe, Co, Mn and Ti suppressed remarkably the cell growth. However, any correlation could not be detected between the effect of alloying elements on the intragranular precipitation of γ′ phase and that on the cell growth on aging. On the other hand, the quantitative correlation was found out between the effect on the grain growth in the Cu-2%Be alloy at 1093 K and that on the cell growth at 523 K.
It is considered from the above facts that the effect of alloying elements on the grain boundary reaction may substantially be that on the mobility of advancing boundaries of cells rather than that on the chemical driving force for the cell growth.

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Effect of cold-working on the damping capacity of furnace-cooled or water-quenched Al–Zn alloys with 0–100%Zn was studied by varying the reduction in area. Measurements of the logarithmic decrement δ and the rigidity modulus G were carried out by the inverted torsion pendulum method at a frequency of 1 Hz. The hardness Hv and the specific weight S were measured by a micro-Vickers hardness tester and by the Archimedean method, respectively.
Except the water-quenched alloys with 70–90%Zn, the heat-treated alloys have generally a low value of δ. The magnitude of δ in the alloys subjected to the heat-treatment should be attributable to the viscous flow at the grain-boundary between the hard α and the soft β phases. Upon cold-working, the δ of any alloys, especially alloys with 50–70%Zn, considerably increases with reduction in area. The increase in δ must be mainly due to the increased boundary effect resulting from grain refinement.
The hardness of the alloys with 10–70%Zn water-quenched from 673 K is considerably higher than that of the alloys furnace-cooled. On the other hand, the furnace-cooled alloys with 80–90%Zn show a Hv value higher than the water-quenched ones. With approach to the eutectoid composition, the Hv value after cold-working decreases. The alloys water-quenched from 573 K or furnace-cooled from 573 and 673 K increase in G with Zn content, while those after water-quenching from 673 K yield a minimum value at 50%Zn. The G value after cold-working is nearly constant up to 40%Zn and increases rapidly with Zn content above 40%, regardless of the prior heat-treatment. The S increases with Zn content, but its value is generally as small as 4.8 Mg/m³ even for the Al-70%Zn alloy.

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Young’s modulus, the thermal expansion and the magnetization at 120–700 K and the crystal structure at room temperature were investigated for annealed Mn–Ge–Fe alloys with various crystal structures such as β+γ, γ, γ+ε and ε phases. Young’s modulus vs temperature curves of the ternary alloys consisting of β+γ and γ phases show a reversible change at a heating and cooling speed of about 27.8×10⁻³ K/s, and have distinct minima and maxima, corresponding to the Néel point of the γ phase T_N(γ) and the β\ ightleftarrowsγ reversible phase transformation point T_t below about 10 at% iron, and the alloys containing iron more than 10 at% show only the T_N(γ). The Elinvar characteristic appears around the temperature which corresponds to a minimum or a maximum of Young’s modulus vs temperature curves. However, the Young’s modulus of the ternary alloys consisting of the γ+ε and ε phases shows a minimum point of T_N(ε) or T_N(γ), and the Elinvar characteristic around these points becomes rapidly less pronounced with increasing iron content.
The composition range of the Mn–Ge–Fe alloys whose temperature coefficients of Young’s modulus are about zero or −20×10⁻⁵ is relatively narrow with iron concentration, and it widens mostly at the composition of Fe-70 at%Mn. This composition range has no relation to that of the Fe–Mn–Ge ternary alloys reported previously.

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The microscopic solidification structure of a Pb–Sb eutectic alloy prepared by the twin-roll rapid solidification process has been examined to understand cooling characteristics of the process. The result shows that the average size and the area ratio of globular structure mainly consisting of Sb have minima for a certain roll rotation speed and decrease with decreasing initial roll gap. The effect of melt flow rate on the structure has not been detected under the adopted experimental conditions.
Regarding the relationship between the solidification structure and the cooling rate of melt, a preliminary experiment of the rapid quenching from melt has revealed that with increasing cooling rate the structure consisting of Sb phase becomes globular and the average size decreases.
Furthermore, velocity and temperature fields of the process were estimated using a mathematical model to discuss effects of key process parameters on cooling rates of the rapidly solidified metallic ribbons. The estimated results show that under the adopted experimental conditions the mean cooling rate in the melt region between rolls has a maximum for a certain roll rotation speed and increases with decreasing initial roll gap. These theoretical predictions qualitatively agree with results obtained from the observed solidification structure.

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