Fracture Toughness of Al_2o_3-Ni Composites Prepared by Powder Metallurgy Method

摘要

In the present study, we investigated the fracture toughness of alumina matrix composite reinforced with nickel at ratios of 1%, 3%, 5% and 7% by weight prepared by powder metallurgy method. Sintering process was performed at 1425 and 1440°C for 1h in graphite powder. The fracture toughness of test materials for 1425°C and 1440°C were 5.1, 5.2, 6.0, 6.7 MPa.m~(1/2)and 5.4, 5.7, 6.1, 7.1 MPa.m~(1/2) respectively. It was found that the more Ni content leads the higher fracture toughness because of crack arresting/energy absorbing effect of metallic ductile Ni particles. The distribution of reinforced nickel particles in the matrix was characterized by optical and SEM and the presence of nickel and alumina phases were confirmed with EDS and XRD analysis. XRD analysis showed that it has not been detected any oxidized Ni body in the composite. Optical and SEM studies revealed that the distribution of nickel particles is uniform in the alumina matrix.Keywords: Fracture toughness, AI_2O_3-Ni composite, hardness, sintering, powder metallurgy.