热压烧结温度对SiC颗粒增强铝基复合材料微观组织及力学性能的影响

EFFECT OF HOT PRESSING TEMPERATURE ON MICROSTRUCTURE AND MECHANICAL PROPERTIES OF SiC PARTICLE REINFORCED ALUMINUM MATRIX COMPOSITES

本文在540—640℃温度范围内,研究了真空热压温度对15%(体积分数)SiCp/2009Al复合材料的微观组织和力学性能的影响.复合材料的致密度随热压温度升高而增加,在580℃达到最大值,高于580℃时下降.TEM界面观察发现:热压温度为540和560℃时复合材料界面结合较弱,界面出现开裂现象;当热压温度为580和600℃时界面清洁、结合较好;当温度高于620℃时,复合材料界面有MgAl_2O_4和Al_4C_3形成.复合材料的强度和塑性均在580℃取得最佳值.拉伸断口观察发现:热压温度低于560℃时,复合材料的断裂以界面脱黏为主;热压温度在580—600℃之间时,复合材料以基体的韧性断裂和颗粒的断裂为主;热压温度高于620℃时,复合材料界面处MgAl_2O_4和Al_4C_3脆性相的形成使界面开裂,复合材料的断裂为基体韧性断裂、界面开裂以及SiC颗粒断裂.

The effects of hot pressing temperature on microstructures and tensile properties of 15%（volume fraction） SiC_p/2009Al composites were investigated in this paper.The relative density of the composites increased rapidly with increasing the hot pressing temperature up to 580℃and decreased with further increasing the temperatures.TEM observations revealed that the interface bonding was quite weak with the interface crack when the hot pressing temperature was below 560℃.When the composites were hot pressed at 580 and 600℃,the interface was clean and had a good interface bonding.The MgAl_2O_4 and Al_4C_3 formed at the interfaces when the hot pressing temperature was above 620℃.Tensile tests indicated that the composite fabricated at 580℃exhibited the optimum strength and ductility.Proctography revealed that for the composite fabricated at the hot pressing temperature below 560℃,the fracture mechanism was mainly the interfacial debonding.For the composite fabricated at 580 and 600℃,the fracture mechanism of the composite was the matrix ductile fracture and the SiC particle fracture,When the hot pressing temperature was above 620℃, the interface fractured along MgAl_2O_4 and Al_4C_3,and the fracture mechanism of the composite was the matrix ductile fracture,the interface crack and the particle fracture.