Effects of La and Mg on Microstructure and Mechanical Property of Alâ€15Si Alloy

Abstract

The effects of La on the microstructures and mechanical properties of Alâ€15Si alloy were investigated, and the results showed that 0.3% La could availably modify the Alâ€15Si alloy. The morphology of the eutectic Si obviously changed into the short flake and the dot shape, and the angle of primary Si was refined to bluntness with the contents of La increasing from 0.1 % to 0.3%. In addition, the effects of Mg on the microstructures and mechanical properties Alâ€15Siâ€0.3La alloy were studied. The optical micrographs showed that the eutectic Si were further refined to the shorter bar the dot shape, and the amount of primary Si reduced with the increase of Mg addition. The formation of Mg2Si strengthening phase improved the mechanical properties of the modified Alâ€15Siâ€0.3La alloy. Compared with Alâ€15Si alloy, the tensile strength and the elongation of Alâ€15Siâ€0.3Laâ€2.0Mg alloy increased 41.4% and 40%, respectively.