热处理及SiC颗粒尺寸对15%SiC_p/6061Al复合材料性能的影响

Mechanical Properties of 15%SiC_p/6061Al Composites with Heat Treatment and Different SiC_p Sizes

采用粉末冶金法制备了体积分数15%的、不同粒度SiC颗粒增强的6061Al基复合材料,研究了固溶-时效热处理工艺对复合材料屈服强度、抗拉强度、延伸率的影响规律,确定了最佳热处理工艺参数,揭示了Si C颗粒(SiC_p)粒度变化对复合材料力学性能的影响规律,研究表明:随SiC_p粒度的增加,SiC_p/6061Al基复合材料的弹性模量基本不受影响;但复合材料的屈服强度、抗拉强度逐渐降低,延伸率、断面收缩率先增大后减小。当SiC_p粒度增加到10μm时,复合材料屈服强度、抗拉强度出现明显下降,同时复合材料延伸率和断面收缩率由提高变为降低,其原因是复合材料断裂失效机制由基体撕裂控制转变为增强颗粒开裂与基体撕裂共同控制。拉伸断口扫描电镜(SEM)分析表明,随着SiC_p粒度的增加,SiC_p/6061Al复合材料中出现颗粒开裂并且数量逐渐增加。

15% SiCp/6061Al （volume fraction） composites were fabricated by powder metallurgy method. The effects of solid solu- tion aging heat treatment process on yield strength, tensile strength and elongation were studied, and the optimal heat treatment process parameters were obtained, The influence of SiC particle （ SiCp ） size on the mechanical property was also revealed. The results showed that the elasticity modulus was nearly unaffected by SiCp size. The yield strength and tensile strength decreased with SiCp size increasing, while the elongation and reduction of cross-section area increased firstly and then decreased with SiCp size increasing. The yield strength and tensile strength decreased greatly when the added SiCp size was larger than 10 μm, while the elongation and reduction of cross-section area decreased instead of increasing. The possible reason was that the fracture mechanism changed from matrix tearing fracture to combined fracture of matrix tearing and particle cracking. The tensile fracture surface was observed by scanning electron microscope （SEM）, and the result indicated that the cracked SiCp in 15% SiCp/6061Al composites increased with the increase of SiCp size.