Microstructure and mechanical properties of pressureless sintered Al2O3/SiC nanocomposites

Alumina/silicon carbide nanocomposites fabricated by hot-pressing techniques are found to exhibit the extremely improved fracture strength even at high temperatures and 3 to 4 order of magnitude enhanced creep resistance. In this work the pressureless sintering was applied to fabricate Al2O3/SiC nanocomposites with aiming to break through the cost performance and near-net-shape production problem. MgO and/or Y2O3 were selected as sintering additives, and high density of over 98% was achieved. TEM observation revealed that the nano-sized SiC particulates were mainly dispersed within the matrix grains. The fracture strength was improved to 1000 MPa by dispersing 5 vol.% SiC even for sinter/Hipped nanocomposites. This strength value is almost the same level with that obtained by hot-pressing techniques. (C) 1997 Acta Metallurgica Inc.