Study On The Microstructure And Mechanical Properties Of As-cast And Semi-solid N-SiC_p/AZ91D Composites

The magnesium alloy is one of the widely used metal materials, but low mechanicalproperties make the use of magnesium alloy limited, the particles reinforcing magnesiummatrix composites can make up for the inadequacy of the performance of magnesium alloyseffectively. In this paper, n-SiCp/AZ91D magnesium matrix composites were fabricated bycast with stirring and for semi-solid isothermal treatment. Microstructure, phase composition,semi-solid organization, fracture morphology were analyzed by optical microscope, scanning,electron, microscopy. The mechanical properties of n-SiCp/AZ91D were tested respectivelyby microhardness tester, electronic universal testing machine, wear testing machine. Analyzeparticles reinforced mechanism and organization evolution behavior of the composite insemi-solid isothermal treatment process. Conclusions were as follows:(1)The microstructure of n-SiCp/AZ91D composites of different content of n-SiCpwasanalyzed, which found that the grains of AZ91D magnesium alloy were obviously refined bythe addition of n-SiCp, and the addition of1.5wt.%n-SiCpexhibited the best refined effect.(2)The mechanical properties of AZ91D magnesium alloy and n-SiCp/AZ91Dcomposites were tested, which found that the addition of n-SiCpcould considerably improvethe mechanical properties of AZ91D magnesium alloy. The mechanical properties ofcomposites dropped when the addition of n-SiCpincreased to2.0wt.%. Among those kinds ofcomposites, the addition of1.5wt.%n-SiCpexhibited the best enhanced effect. Tensile strength,hardness, bending strength, compressive strength, increased by15.8%,24.3%,6.3%,36.1%respectively.(3)After semi-solid isothermal treatment at different temperature and time for1.5wt.%n-SiCp/AZ91D composites. The microstructure was analyzed, which found that theprocess parameters of575℃and30min were most suitable for refine the semi-solidorganization of composites, the size of grain is moderate and the shape of grain is spherical.The tensile properties of n-SiCp/AZ91D composites which have been heat treated were higherthan those composites which haven’t been heat treated, and the tensile strength of1.5wt%n-SiCp/AZ91D increased by11.6%.