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以A357铝合金和SiC_p粉作为原料,采用双级搅拌桨在不同工艺参数下对SiC_p含量为20%的A357复合材料进行搅拌铸造,研究了不同工艺参数对SiC_p分布均匀性的影响。对制得的SiC_p/A357复合材料进行T6热处理,采用扫描电镜、硬度测试及拉伸试验,分析了热处理前后组织和力学性能的变化。结果表明,采用双级搅拌桨在搅拌温度为610℃,搅拌转速为800 r/min,搅拌时间为20 min下制备的复合材料中SiC_p分布均匀性最佳。经T6热处理后,复合材料的抗拉强度和硬度明显上升,抗拉强度达到345 MPa,硬度(HB)为123.3,相比铸态分别提高66%和48.6%。断口分析表明,SiC_p/A357复合材料的断裂机制为界面脱粘、Si C颗粒的断裂和基体合金的韧性断裂的混合机制。
A357 aluminum alloy and SiC_p powder were used as raw materials. A357 composite with SiC_p content of 20% was stirred and cast at different process parameters by two-stage mixer. The effects of different process parameters on the uniformity of SiC_p distribution were studied. The prepared SiC_p / A357 composites were treated by T6 heat treatment. The changes of microstructure and mechanical properties before and after heat treatment were analyzed by scanning electron microscopy, hardness test and tensile test. The results show that the SiC_p distribution in the composites prepared by two-stage impeller is the best at 610 ℃, 800r / min and 20min. After T6 heat treatment, the tensile strength and hardness of the composites increased obviously, the tensile strength reached 345 MPa and the hardness (HB) was 123.3, which increased by 66% and 48.6% respectively compared with as-cast. Fracture analysis shows that the fracture mechanism of SiC_p / A357 composites is the interfacial debonding, the fracture mechanism of Si C particles and the ductile fracture of matrix alloy.