Effects of Heat-treatment Temperature on Properties of Co-continuousBeta-Si$lt;inf$gt;3$lt;/inf$gt;N$lt;inf$gt;4$lt;/inf$gt; Reinforced Al Matrix Composites

The co-continuous -Si 3 N 4 reinforced Al matrix composites were fabricated through squeeze casting of porous -Si 3 N 4 preforms with porosity of 53.43% which obtained by pressureless sintering. The influences of heat-treatment temperature on the microstructures and mechanical properties of co-continuous -Si 3 N 4 reinforced Al matrix composites were investigated. With the heat-treatment temperature increase, the degree of interfacial reaction, dislocation density increase, and vickers hardness increases, while fracture toughness decreases, accompanied by flexural strength increasing until 850 and then decreasing. The fracture mode of composites changes gradually from ductile intergranular rupture to brittle intergranular rupture. When being heat-treated at 850, the composites obtain the optimum mechanical properties with the reaction layer of about 20-50 nm.