MA法によるAl₂O₃粒子分散Al–4%Cu複合材料の時効硬化に及ぼす結晶粒径の影響

抄録

Age-hardening behaviors of Al₂O₃ particle dispersed Al–4 mass%Cu composites produced by mechanical alloying were investigated by Vickers microhardness test, X-ray diffraction analysis, scanning and transmission electron microscopy. In the MA composites, the Al₇Cu₂Fe compound was observed in the matrix after solution treatment, because of contamination of Fe atoms during MA. A lot of stable θ phases precipitated on grain boundaries in the early stage of aging, since MA treatment remarkably refined the grain size. The amount of age-hardening of the MA composites significantly decreased compared with that of Al–4%Cu alloy produced by ingot metallurgy. This decrease in the age-hardenability was attributed to the decrease in Cu content of the matrix due to the formation of Al₇Cu₂Fe and the precipitation of θ on grain boundaries in the early stage of aging. The time to the peak hardness during aging of the MA composites was shortened with increasing the volume fraction of Al₂O₃ particle.