Microstructure,characterisation,and superplasticity of alumina/carbon nanocomposite

Abstract

A nanocomposite consisting of a fine grained alumina matrix and carbon nanoparticles was produced by hot pressing. Compressive deformation tests were performed on this material at T = 1400°C up to true strains of -70%. In all cases true strain rates of up to 2 × 10^-4 s^-1 corresponded to low flow stresses (<50 MPa). No cavitation was observed at grain boundaries and little microstructural changes were found to accompany the deformation. Grain boundary sliding accommodated by diffusional mechanisms contributed to the main part of deformation. It is shown that the deformation results are consistent with a diffusivity of the grain boundaries unaffected by the presence of the carbon nanoparticles. The effect of carbon particles lies primarily in a reduction in grain growth without increase in flow stress.