Abstract
We clarify elevated temperature strength and deformation mechanisms of the eutectic Al-Si alloy (AC8A) matrix composites reinforced by 15 vol% and 20 vol% FeCrSif and then construct the constitutive equation of the elevated temperature deformation. Compression test was carried out by strain rate rapid change method on the materials under the conditions of the temperatures from 648 to 723 K and the strain rates between 3 ×10-5 and 1×10-3 s-1. As the results, the flow stress of all aluminum alloy matrix composites was increased with increasing volume fraction of the reinforcements. Threshold stress, which was calculated using a stress exponent of 5, decreased with increasing temperature. The values of the activation energies for FeCrSif/AC8A were close to the activation energy of the lattice diffusion for pure aluminium. Experimental results suggested that the dominant deformation mechanism in FeCrSif/AC8A was the climb-controlled dislocation creep controlled by the lattice diffusion. By using the constitutive equation obtained in this study, it is possible to estimate the elevated temperature strength of FeCrSif/AC8A.
