複合電析膜加熱法によるNi-Al合金膜の組織と硬度

抄録

Electrodeposited composites of Ni-metallic Al particles about 9μm in diameter have been successfully prepared in the form of flat, 400μm-thick films ranging in composition from 0 to 28.3at% Al. The films were then heated at 800°C for 3h. The structures and hardness of the resultant films were then studied by X-ray diffraction, X-ray microanalysis, and measurement of Vickers hardness from room temperature to 750°C. It was found that the matrix and the particles reacted readily to form stable phases: the Ni-5at% Al alloy was a single-phase alloy of fcc solid solution; the Ni-16 and 17at% Al alloys were dual phase alloys of fcc solid solution and Ni₃Al; the Ni-25at% Al alloy was a single phase alloy of Ni₃Al; and the Ni-28.3at% Al alloy was a dual phase alloy of Ni₃Al and NiAl. All the alloys contained small Al₂O₃ particles, which were found initially to be consist of hydroxide films covering metallic Al particles. The room-temperature hardness of the alloys increased with the Al content. Hot hardness measurement of Ni-60vol% Ni₃Al alloy showed an inverse temperature dependence of hardness, which is characteristic of the Ni₃Al phase.