Abstract

Hybrid A1_2O_3-TiC ceramic particle reinforced 6061 and 5083 Al composite powders were prepared by the combination of twin rolling and stone mill crushing process, followed by consolidating processes of cold compaction, degassing and hot extrusion. The composite bar consists of lamellar structure of ceramic particle rich area and matrix area, in which the hybrid was decomposed into each TiC of about 3-4mutextrmm and AI_2O_3 particles of about 1-2mutextrmm in diameter. It also found that fine Mg_2Si precipitates of about 30 nm were embedded in the matrix, which have grains of about 3 mutextrmm. Higher UTS was measured at the 5083 composite bar compared to the conventionally fabricated composite, due to again refinement effect by the rapid solidification. No particle was shown to form in the interface between the matrix and reinforcement, whereas carbon was diffused into the matrix.

• Keywords: Metal matrix composite;Rapid solidfication;Al alloys;Stone mill process;