Al-Sc Master Alloy Prepared by Mechanical Alloying of Aluminum with Addition of Sc₂O₃

抄録

Al–Sc master alloy was prepared by the powder metallurgy route from the initial composition of Al₉₀(Sc₂O₃)₁₀ mixture. Aluminum powder was mechanically alloyed with addition of Sc₂O₃, which is much less costly than the metallic Sc, and fine Sc₂O₃ particles became uniformly dispersed in the matrix of Al. During consolidation by SPS at 873 K for 3.6 ks of mechanically alloyed powder mixture, Sc₂O₃ was decomposed and Al₃Sc and Al₂O₃ are formed by solid-state reaction. Subsequently, SPS billets were hot-extruded at 773 K with a reduction of 1/12. Obtained extruded P/M material of Al–Sc master alloy was added to Al–4.5%Cu alloy melt and cast into the copper mold in order to attest its grain refining effect. Apparent grain refining was attained in the ingot of Al–4.5%Cu–0.55%Sc alloy and thus effectiveness of extruded P/M material from mixture of Al₉₀(Sc₂O₃)₁₀ as the Al–Sc master alloy was clearly attested. However, break down of covered oxide film of each powder particle by large plastic deformation is considered to be necessary to complete melting of added Al–Sc master alloy in the Al alloy melt.