PREPARATION, MICROSTRUCTURE, AND MECHANICAL-PROPERTIES OF SILICON-CARBIDE DYSPROSIA COMPOSITES

Composites of silicon carbide (SiC) with up to 30 vol% of dysprosia (D y2O3) were fabricated by hot pressing and hot isostatic pressing, The effects of Dy2O3 dispersions on the microstructure and on selected mec hanical properties of the composites were investigated, When 10-15 vol % of Dy2O3 was dispersed in the SiC matrix, the fracture toughness inc reased by similar to 40%, whereas the flexural strength was comparable to that of unreinforced SiC. The increased fracture toughness was due to crack deflection, in conjunction with crack-interface grain bridgi ng, and was not related to a phase transformation of Dy2O3 in the matr ix.