EFFECTS OF POSTSINTER HOT ISOSTATIC PRESSING PROCESSES ON MICROSTRUCTURES AND MECHANICAL-PROPERTIES OF AL2O3-CR3C2 COMPOSITES

The relative density and mechanical properties of Cr3C2 particulate reinforced Al2O3 matrix composites have been investigated as a function of the Cr3C2 content and of the temperatures used for hot isostatic pressing (HIP) as a post-sinter heat treatment. The best mechanical properties were obtained by hot isostatic pressing at 200 MPa and 1500-degrees-C for 2 h, giving material with a fracture strength and toughness of 736 MN m-2 and 7.9 MN m-3/2. These values were similar to those of uniaxially hot pressed composites. The dependence of the mechanical properties on microstructure development is discussed in terms of flaw size. Al2O3 grain size, and density. (C) 1994 The Institute of Materials.