搅拌摩擦加工制备铝基复合材料的组织和力学性能

Microstructure and mechanical properties of aluminum matrix composites by friction stir processing

采用搅拌摩擦加工方法制备铝基SiC复合材料,研究SiC颗粒在复合材料中的分布均匀性问题,并对复合材料的力学性能及断口形貌进行分析.结果表明:1、2、3道次加工后SiC颗粒在复合材料中出现漩涡状和带状团聚现象;经4道次搅拌摩擦加工后复合层中SiC颗粒均匀弥散分布在基体金属中,复合层组织发生明显细化;添加SiC颗粒4道次加工后复合材料显微硬度提高,抗拉强度降低.搅拌摩擦区的显微硬度平均值为68HV,为基体金属显微硬度(45HV)的1.5倍;抗拉强度降低为176MPa,为基体金属的81%;复合材料拉伸试样总体表现为韧性断裂,断裂机制包含韧性断裂以及SiC颗粒与基体结合界面的撕裂.

Friction stir processing was used for the fabrication of SiC composites materials of aluminum substrate and the uniformity of distribution of SiC particles in the composite was investigated. And the mechanical properties and fracture morphology of the composites were analyzed, also. The result showed that agglomeration of SiC particles took place in the composite in the form of swirl and band after single pass, 2-passes and 3-passes of friction stir processing（FSP）. SiC particles of the composite layer would be uniformly distributed in the base metal and the mierostructure would obviously be refined after 4-passes of friction stir processing. Moreover, the eomposite＇s mierohardness increased and tensile strength decreased after 4-passes of friction stir processing. The average micro-hardness of friction stir zone was 68 HV, which was as 1.5 times much as the base metal hardness （45 HV）. Tensile strength decreased to 176 MPa, which was 81% of the base metal. Fracture of the composites exhibited the characteristics of ductile fracture, the fracture mechanism included the ductile fracture and the tear of the combination of SiC particles with matrix interface.