Abstract The effects of Sr addition on the microstructure and mechanical properties of in-situ ZrB2 nanoparticles reinforced AlSi9Cu3 composites synthesized via direct melt reaction were systematically investigated. The addition of Sr could modify the morphology of eutectic silicon particles and refine the second dendrite arm spacing of α-Al dendrites. Alternatively, the ZrB2 nanoparticles were also refined and distributed more homogenously, and nanoparticle agglomerations were reduced with the addition of Sr element. The results demonstrated that the addition of 0.06 wt% of Sr element can reach the optimal refinement of the second dendrite arm spacing of α-Al and the modification of eutectic Si. In this case, the ultimate tensile strength, yield strength and elongation reached 330 MPa, 226 MPa and 15.70%, respectively, which were remarkably enhancement in comparison with the base alloy.

中文翻译：

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Sr添加对原位ZrB2纳米颗粒增强AlSi9Cu3复合材料微观结构和力学性能的影响

摘要 系统研究了Sr添加对直接熔融反应合成的原位ZrB2纳米颗粒增强AlSi9Cu3复合材料的微观结构和力学性能的影响。Sr的加入可以改变共晶硅颗粒的形貌，细化α-Al枝晶的第二枝晶臂间距。或者，ZrB2 纳米颗粒也得到了细化和更均匀的分布，并且通过添加 Sr 元素减少了纳米颗粒的团聚。结果表明，添加0.06 wt%的Sr元素可以达到α-Al二次枝晶间距的优化细化和共晶Si的变质。在这种情况下，极限抗拉强度、屈服强度和伸长率分别达到了 330 MPa、226 MPa 和 15.70%，