Microstructure, mechanical properties and strengthening mechanism of SiCP/AZ91 composites
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摘要: 通过搅拌铸造工艺制备出SiCP体积分数分别为2%、5%、10%和15%的4种5 μm SiCP/镁合金（AZ91）复合材料。对5 μm SiCP/AZ91进行了固溶、锻造和热挤压。通过与AZ91对比，研究了SiCP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：SiCP/AZ91热变形后的晶粒尺寸取决于SiCP的体积分数。SiCP的体积分数由0%增加到10%时，SiCP/AZ91热变形后的平均晶粒尺寸减小；当SiCP颗粒继续增加到体积分数为15%时，平均晶粒尺寸反而增大。SiCP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。SiCP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。Abstract: The four kinds of 5 μm SiCP/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 SiCP 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 SiCP/AZ91 depends on the volume fraction of SiCP. The average grain size of composite matrix decreases as the volume fraction increased from 0% to 10%, the grain size increases as SiCP volume fraction continuing increased to 15%. The addition of SiCP can improve the yield strength and modulus of AZ91 significantly, and they increase with the volume fraction of SiCP. The strengthening effects of SiCP 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.
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