In-situsynthesized（Al3Zr+Al2O3）p/A356compositesbydirectmeltreactioninAl-Zr-Osystem

A novel in situ reaction system Al Zr O was developed. In situ Al 3Zr and Al 2O 3 particulate reinforced A356 alloy matrix composites have been fabricated by direct melt reaction method. The results show that the maximum sizes of Al 3Zr and Al 2O 3 particulates synthesized in the system ZrOCl 2 A356 are 1 μm and 3 μm respectively, and they are well distributed in the matrix. The investigation shows that the Al 3Zr crystal is in the shape of polyhedron and rectangle. There is a faceted growth phenomenon on Al 3Zr crystal surface. It is firstly found that the Al 3Zr crystal grows in the mechanism of twinning. The twinning plane is (1 1 4), and the twinning direction is [2 2 1] . The crystal morphology of in situ α Al 2O 3 particulate is rectangle or sphere. Furthermore, (Al 3Zr+Al 2O 3) p/A356 composites have not only higher tensile strength at room temperature (376.2 MPa) but also higher yield strength (319.4 MPa) and higher tensile strength at elevated temperature (200 ℃) than those of the A356 alloy. The dry sliding wear test shows that the wear resistance of the (Al 3Zr+Al 2O 3) p/A356 composites is greatly enhanced with increasing particulate volume fraction.