Preparation Technology And Mechanical Properties Of SiC_p/AZ91 Composites By Solid Phase Synthesis

Magnesium alloy has good specific strength,specific stiffness,damping damping performance,cutting performance,is widely used in aerospace,automotive,electronic communications,known as the most promising"green engineering material"after aluminum alloy.The disadvantages of magnesium alloy such as low absolute strength and poor high temperature performance limit its application scope.Magnesium matrix composites were prepared by using magnesium alloy as matrix and adding reinforcing phase to it.Magnesium matrix composite material not only inherits the advantages of low density,good specific strength and stiffness,damping and damping performance of magnesium alloy,but also improves the absolute strength,wear resistance and high temperature performance of the composite material.The excellent properties of magnesium matrix composites further expand its application range.In this paper,the SiC_p/AZ91 composite was prepared by solid state recycling using AZ91 magnesium alloy as matrix material and SiC particles as reinforcing phase.The microstructure and mechanical properties of the SiC_p/AZ91 composite were analyzed by optical microscope,scanning electron microscope,X-ray diffractometer,vickers hardness tester and electronic universal tensile testing machine.The microstructure and mechanical properties of micron,nanometer and dual-scale SiC_p/AZ91 composites were studied.Because of the excellent properties of the dual-scale SiC_p/AZ91 composites,the effects of extrusion temperature on the microstructure and mechanical properties of the dual-scale SiC_p/AZ91 composites were further investigated.SiC_p/AZ91 composites with mass fractions of 1wt.%,2wt.%,3wt.%and 4wt.%were prepared by solid state recycling with 10 m SiC_p as the reinforcing phase.When the SiC_p mass fraction is 3%,the composite material has the best mechanical properties,with the tensile strength,yield strength and hardness of 333MPa,211MPa and 89.5HV,respectively.Using SiC_p at different scales as the reinforcing phase,the solid state recycling method was used to prepare 1wt.%n-SiC_p/AZ91,3wt.%m-SiC_p/AZ91,(1wt.%n+2wt.%m)-SiC_p/AZ91 composites.The performance of the dual-scale SiC_p/AZ91 composite was the best,with the hardness of 92.8HV,the tensile strength and yield strength of 345MPa and 225MPa,respectively.By comparing the microstructure and properties of dual-scale composites at extrusion temperatures of 380?,410?and 440?.When the extrusion temperature was 410?,the vickers hardness,tensile strength and yield strength of the dual-scale SiC_p/AZ91 composite were the highest.