Processing and Mechanical Properties of Pressureless-Sintered Niobium-Alumina-Matrix Composites

Niobium-alumina (Nb-Al 2 O 3 ) composites have been fabricated via the pressureless sintering of compacts of intensively milled Nb-Al 2 O 3 mixtures. Strength and fracture toughness of the composites increase as the niobium content increases. For a composite that contains 50 vol% niobium, strengths of up to 680 MPa, with a corresponding fracture toughness of 6.3±0.3 MPa.m 1/2 and hardness of 6.4 GPa, have been obtained.