Microstructure and tensile properties of Si 3N 4p/2024Al composite fabricated by pressure infiltration method

Abstract

2024Al matrix composite reinforced with 45 vol.% Si 3N 4 particles (Si 3N 4p/2024 composite) with average particle size of 1.5 μm was fabricated by pressure infiltration method. The tensile behaviour and microstructure of Si 3N 4p/2024 composite were investigated. β-Si 3N 4 was the main reinforcement, while α-Si 3N 4 and few large Si particles were also observed in composite. Few aligned linear dislocations were observed in Si 3N 4 particles due to internal and thermal stresses. MgAl 2O 4 was observed at Si 3N 4–Al interface. Fracture of Si 3N 4p/2024Al composite was characterized by brittle fracture, indicating strong Si 3N 4–Al interfacial bonding. Dislocation density in Si 3N 4 particles and Al matrix increased after tensile testing.