Effect Of Matrix Alloy Composition On The Flexural Property Of SiCp/Al Composites

The development of automobile and aerospace industry required to light weight, high performance, low cost, corrosion, safety, environmental protection, energy saving and other advantages. Reducing the structure weight to achieve lightweight has a significant positive effect on aircraft, automobile manufacturing. Therefore the prospects for the development of low density, high strength, high specific stiffness of SiCp/Al composites are very broad in the aerospace and automobile industry.In this paper, the effect of matrix alloy composition on flexural property is researched with SiCp/Al the content of Si is 7%?10%?12%?15%(mass fraction, similar hereinafter), Mg is 3%?5%?7%?9%, respectively. Using the factorial design of Design-Expert, we designed sixteen experimental schemes of matrix alloy components. After melting experiments, the alloys are cutting into sample. Scanning electron microscopy (SEM) is used to analysis the microstructure of alloy, X ray diffraction (XRD) is used to analysis the phase composition of the matrix alloys, and microhardness tester is also used to measured microhardness of matrix alloys. Then the alloys prepared under the same condition with the same parameter of SiC particles to fabricate SiCp/Al composite, the resulting composite material is cut, the electronic liquid density meter DH-300 is used to measure the density,use Rockwell hardness hardness tester and computer-controlled electronic universal testing machine with WDW-10 are used to test hardness and flexural properties, respecatively.It is showed that the matrix of Al-Mg-Si alloy are mainly primary a-Al phase, flaky and strip eutectic Si, plate-like primary Si and black skeleton-like Mg2Si phase. While a gray skeleton-like phase and a small amount of Al8Si6Mg3Fe, Al9Si,Al0.3Fe3Si0.7, Al0.5Fe3Si0.5 are also existed in matrix alloy.With the change of Si and Mg contents, strengthening phase Mg2Si content changes, changes grain size and hardness of the alloys also change, which induce the mechanical properties of composite materials are different. It can be drawn the conclusion that when the compositions of the matrix alloy are Al-9Mg-15Si,Al-3Mg-7Si,Al-3Mg-12Si, Al-7Mg-7Si, Al-3Mg-15Si, Al-7Mg-10Si, the hardness of the composite is higher To SiCp/Al composite,when the content of Mg was 3%, the flexure strength decreases with the increase of Si content, when the content of Mg was 9%, the flexture strength increases with the increase of Si content.. When the content of Si is 7%, the flexure strength increases first and then decreases with the increase of Mg content. When the content of Si is 10%, the flexure strength s decreases and then increases with the increase of Mg content. When the alloy compositions of the matrix are Al-9Mg-12Si, Al-9Mg-15Si, Al-3Mg-7Si, Al-7Mg-7Si, Al-5Mg-7Si, Al-5Mg-10Si, the flexture strength of SiCp/Al composites are higher. Moreover, as the alloy composition of the matrix is Al-5Mg-7Si, the flexure strength of SiCp/Al composites is the highest. Besides, the trend of the change of the hardness of SiCp/Al composites is basically the same as that of the relative density. As the alloy compositions of the matrix are Al-9Mg-10Si, Al-9Mg-12Si, Al-9Mg-15Si, Al-3Mg-7Si, the variation of flexure strength and hardness of the SiC/Al composites is the same. combined with composites density, hardness and flexure strength,it comes to the conclusion that when the alloy compositions of the matrix are Al-3Mg-7Si, Al-7Mg-7Si, the overall performance of SiCp/Al composites are better.