SiCP/AZ91复合材料的显微组织、力学性能及强化机制

通过搅拌铸造工艺制备出SiC_P体积分数分别为2%、5%、10%和15%的4种5 μm SiC_P/镁合金（AZ91）复合材料。对5 μm SiC_P/AZ91进行了固溶、锻造和热挤压。通过与AZ91对比，研究了SiC_P对AZ91基体热变形后显微组织和力学性能的影响规律。结果表明：SiC_P/AZ91热变形后的晶粒尺寸取决于SiC_P的体积分数。SiC_P的体积分数由0%增加到10%时，SiC_P/AZ91热变形后的平均晶粒尺寸减小；当SiC_P颗粒继续增加到体积分数为15%时，平均晶粒尺寸反而增大。SiC_P的加入能显著提高AZ91的屈服强度和弹性模量，并随颗粒体积分数的增加而增大。SiC_P对AZ91基体的强化作用主要源于位错强化、细晶强化和载荷传递作用，其中，细晶强化对屈服强度的贡献最大。

Microstructure,mechanical properties and strengthening mechanism of SiCP/AZ91 composites

The four kinds of 5 μm SiC_P/Mg alloy (AZ91) magnesium matrix composite with the volume fraction of 2%, 5%, 10% and 15%, respectively, were fabricated by stir casting. After the solution treatment, forging and hot extrusion, the effect of SiC_P on the microstructure and mechanical properties of AZ91 matrix were investigated by compared with the monolithic AZ91 alloy. The results show that the grain size of SiC_P/AZ91 depends on the volume fraction of SiC_P. The average grain size of composite matrix decreases as the volume fraction increased from 0% to 10%, the grain size increases as SiC_P volume fraction continuing increased to 15%. The addition of SiC_P can improve the yield strength and modulus of AZ91 significantly, and they increase with the volume fraction of SiC_P. The strengthening effects of SiC_P on AZ91 matrix are mainly attributed to dislocation strengthening mechanism, grain refinement and load transfer effect, the grain refinement plays a main role on improving the yield strength.