【摘要】 利用熔体原位反应法制备了(Al2O3+Al3Zr)p/A356复合材料.研究了添加质量分数均为0.2%的Mn和Cr微合金元素对所制备的复合材料微观组织和室温力学性能的影响.SEM分析结果表明:添加微合金元素改善了(Al2O3+Al3Zr)p/A356复合材料的微观组织,原位Al3Zr颗粒和初生α相得到了有效细化,尺寸大部分为2~3μm,增强颗粒均匀分布在A356基体中,颗粒呈球形或椭球形.室温拉伸试验结果表明,添加微合金元素对复合材料的力学性能有一定程度的改善,其抗拉强度σb,屈服强度σs和延伸率δ较添加前分别提高了13.9%,16.9%和10.6%,达到326.1MPa,252.2 MPa和5.2%.SEM拉伸断口形貌分析表明,其断裂属于塑性断裂.更多还原

【Abstract】 The A356 matrix composites reinforced by Al2O3 and Al3Zr particulates were fabricated by the direct melt reaction.Effects of adding 0.2% Mn and 0.2% Cr on the microstructure and mechanical properties of(Al2O3+Al3Zr)p/A356 composites were investigated.The SEM analysis results indicate that the added alloying elements can amend the microstructure of (Al2O3+Al3Zr)p/A356 composites and in-situ Al3Zr particulates and the α-Al are refined effectively.Reinforcement particulates are distributed uniformly in the A356 matrix with sizes about 2~3 μm.The mechanical properties test results show that adding 0.2% Mn and 0.2% Cr can amend the mechanical properties of the composites to a certain degree.The values of the tensile strength σb,yield strength σs and elongation δ reach to 326.1MPa,252.2 MPa and 5.2% respectively,with increments of 13.9%,16.9% and 10.6% compared to those without adding Mn and Cr.The fracture morphology indicates that the fracture of (Al2O3+Al3Zr)p/A356 composites is plastic fracture.更多还原