热处理温度对双连续-氮化硅增强铝基复合材料性能的影响

摘要

The co-continuous-Si3N4 reinforced Al matrix composites were fabricated through squeeze casting of porous-Si3N4 preforms with porosity of 53.43% which obtained by pressureless sintering. The influences of heat-treatment temperature on the microstructures and mechanical properties of co-continuous-Si3N4 reinforced Al matrix composites were investigated. With the heat-treatment temperature increase, the degree of interfacial re-action, dislocation density increase, and vickers hardness increases, while fracture toughness decreases, accompa-nied by flexural strength increasing until 850℃ and then decreasing. The fracture mode of composites changes gradually from ductile intergranular rupture to brittle intergranular rupture. When being heat-treated at 850℃, the composites obtain the optimum mechanical properties with the reaction layer of about 20–50 nm.%通过常压烧结法制备了气孔率为53.43%的多孔氮化硅预制体,并利用挤压铸造法制备双连续-氮化硅增强铝基复合材料,并研究了热处理温度对复合材料显微组织和力学性能的影响。利用位错增殖强化理论和界面反应理论分析复合材料的显微组织和力学性能,结果表明,随着热处理温度的升高,铝合金基体发生位错增殖,-氮化硅增强体和铝合金基体的界面反应程度增强,复合材料的显微硬度增高,断裂韧性降低,弯曲强度先增加后降低,复合材料断裂模式从沿晶韧性断裂转变为沿晶脆性断裂。当热处理温度为850℃,复合材料的界面层厚度约为20~50 nm,其综合力学性能达到最佳。