Feasibility of grain refinement method for AZ91 alloy using commercial Al-SiC composite

Abstract

SiC is well-known as an effective carbon inoculation material for grain refinement of Mg-Al-based alloys. In this study, grain refinement ability of stir-casted Al-SiC composite for Mg-Al-based alloy was investigated to confirm the feasibility of industrial application. Commercialized Al-20 vol.-% SiC composite ingot was used in AZ91 alloy as a grain refiner, and grain size of AZ91 alloy dramatically reduce from 650 to 74 µm and become uniform with 0.7 wt-% Al-SiC composite addition. And acicular type Al-Mn phase existed at the grain boundaries are changed to polygonal type and positioned inside grains after grain refinement. These morphological changes of small grain size and uniform second phases contributed to the excellent mechanical properties of AZ91 alloy.