论文部分内容阅读
A novel in-situ reaction system Al-Zr-O was developed.In-situ Al3Zr and Al2 O3 particulates reinforced aluminum matrix composites were fabricated by the direct melt reaction technique in the Al-Zr-O system.Microstructures of the composites and crystal morphology of in-situ formed Al3 Zr and Al2 O3 particulates were analyzed by scanning electron microscope(SEM) and transmission electron microscope (TEM).Results indicate that in-situ formed Al3 Zr and Al2O3 particles are finer and well distributed in aluminum matrix.Al3 Zr particulates with a tetragonal structure are mainly in the shape of polyhedron.A few of them are in the form of rectangle.The length/width ratio of the rectangular Al3 Zr is less than 2.0 and the maximum size is 2 μm.In addition,a certain number of Al2 O3submicro particles with a hexagonal structure are also generated in this system.Furthermore,it is found that Al3 Zr crystal grows by the mechanism of twinning.The twin plane is (114).The twinning direction is [221].The tensile tests show that the composites synthesized in the Al-Zr-O system exhibits high strength and ductility.There are a lot of ripples with fine particles on the fracture.The principal strengthening mechanisms for (Al3 Zr+ Al2 O3)p/Al composites may include Orowan strengthening,grain-refining strengthening,solid-solution strengthening and dislocation strengthening.