抄録
The solidfied structure and phase decomposition during tempering of splat quenched Al-Hf alloys were electron microscopically examined. The solid solubility of Hf in the splat quenched Al-Hf alloy extends up to 10%. The grain boundary mobility of the splat quenched Al-Hf alloy is so high that discontinuous precipitation caused by a grain boundary reaction preceds continuous precipitation within grain. Precipitates formed by the grain boundary reaction are fine needle-shaped and have a metastable crystal structure. When the alloy solidifies at a slow rate, an angular precipitate forms within a grain. The microstructure of the angular precipitate and the interaction between moving grain boundary and the precipitate are discussed.
