Preparation of F e 3 S i‐ A l 2 O 3 Nanocomposite Powders by Mechanochemical Reaction of F e 3 O 4 ‐ S i‐ A l Powder Mixtures

Phase evolution and morphology of F e 3 O 4 ‐ S i‐ A l powder mixtures during ball milling from 30 min to 20 h were investigated. A 3‐h critical milling was necessary for the occurrence of mechanically activated combustion reaction. The reaction results in the formation of F e ( S i), F e 3 S i, and α‐ A l 2 O 3 . During ball milling from 3 to 20 h, F e ( S i) and F e 3 S i were combined into disordered F e 3 S i intermetallic and F e 3 S i‐ A l 2 O 3 composite powder was formed. The presence of in situ formed alumina leads to a decrease in crystallite and particle sizes. The F e 3 S i‐ A l 2 O 3 particles after milling for 20 h had a crystalline size of 10~12 nm.