High temperature deformation of an alumina composite reinforced with silicon carbide whiskers

Abstract

Four-point bending creep tests were carried out in air on an alumina matrix composite reinforced with 9.3 vol.% of silicon carbide whiskers. Typical three-stage creep was observed. In the temperature range of 1673-1823 K, the composite exhibited an average stress exponent of 3.8. The activation energy for creep was estimated as ∼820-830 kJ mol-1. Microstructure of the composite was characterized before and after deformation. Dislocation networks and other configurations were observed in samples deformed to large strains. It is concluded that the deformation mechanism consists of intragranular dislocation movement controlled by the lattice diffusion of oxygen ions. © 1995 Elsevier Science Ltd..