Effects of Technical Parameters of Semi-Solid Stirring and Rheo-Rolling on Microstructure of A356-5wt.%B4C Composite Strip

Aluminum boron carbide composite strip was prepared by semi-solid stirring and rheo-rolling, and the effects of process parameters on microstructure of A356-5wt.%B4C composite strip were studied. The results showed that the distribution of B4C particles in the matrix became homogeneous, and the average diameter of alpha-Al and its roundness decreased with the increase of the stirring speed and the stirring time as well as the decrease of the stirring temperature. The average diameter of the primary alpha-Al grain increased with the increase of the roll speed. When the stirring speed was 500rpm, the stirring time was 20min, the stirring temperature was 853K (580 degrees C), and the roll speed was 0.2m/s, the microstructure of A356-5wt.%B4C composite strip was mainly composed of spherical or rosette alpha-Al grains, and the distribution of B4C particles was homogeneous. The hardness of A356-5wt.%B4C composite strip was 98 HV, and the ultimate tensile strength and elongation were 186MPa and 1.8%, respectively. The hardness was improved by 25% comparing with casting alloy A356. The ultimate tensile strength and elongation were improved, respectively, by 28.3% and 5.9%.