Microstructure and Properties of In-Situ Synthesized (Al3Zr+Al2O3)p/A356 Composites
A novel in-situ reaction system Al-Zr-O was developed. In-situ Al3Zr and Al 2 O 3 particulate reinforced A356 alloy matrix composites have been fabricated by direct melt reaction method. The results show that the maximum size of Al3Zr and Al 2 O 3 particulate synthesized in the system ZrOCl2-A356 is 1um and 3um respectively, and they are well distributed in the matrix. The investigation shows that Al3Zr crystal is in the shape of polyhedron and rectangle. There is a faceted growth phenomenon on Al3Zr crystal surface. It is firstly found that the Al3Zr crystal grows in the mechanism of twin. The twin plane is [Formula: see text], and the twinning direction is [Formula: see text]. The crystal morphology of in-situ[Formula: see text] particulate is rectangle or sphere. Furthermore. ( Al 3 Zr+Al 2 O 3) p / A356 composites have not only higher tensile strength at room temperature (376.2MPa) but also higher yield strength (319.4MPa) and higher tensile strength at elevated temperature (200°C) than that of A356 alloy.