Plastic Deformation Mechanisms in SiC‐Whisker‐Reinforced Alumina

Abstract

SiC‐whisker‐reinforced Al2O3 samples (SiCw/Al2O3), obtained from three different manufacturers, containing 0–30 vol% SiC have been crept under compression at 1400°C in flowing argon. Compressive creep tests and microstructural observations have been used to characterize the plastic deformation mechanisms. The presence of whiskers decreased the creep rate by reducing grain‐boundary sliding. Damage formation was increased, however, because the whiskers acted as stress concentration sites. For specimens with whisker loadings greater than 15%, the absolute creep rate was not strongly dependent on whisker concentration, and the formation of cavitation damage was negligible below a critical stress that depended on the fabrication procedure of the specimen. This creep regime was characterized by a stress exponent of approximately 1, in which deformation occurred primarily by diffusional flow. For the materials with less SiC, the deformation occurred primarily by grain‐boundary sliding.