挤压铸造法制备Al/AlN陶瓷基复合材料

Squeeze Casting of Al/AlN Ceramic Matrix Composites

通过碳热还原法制备气孔率可控的多孔氮化铝预制体,利用挤压铸造工艺制备出Al/AlN陶瓷基复合材料。氮化铝与铝不发生化学反应,避免了过度的界面反应对复合材料性能的不利影响。随着复合材料中铝合金含量的增加,复合材料的弯曲强度和显微硬度下降,断裂韧性增加。铝合金的断裂模式是韧性撕裂,氮化铝晶粒以穿晶断裂为主。复合材料的增韧机制主要有裂纹桥联增韧和微裂纹增韧。

The Al/AIN ceramic matrix composites were fabricated through the squeeze casting of porous A1N preforms with varied porosities obtained by carbothermal reduction. The avoiding of excessive interface reaction between AIN and AI was beneficial to the mechanical properties of the composites. With an increase in the AI content of the composites, the Vickers hardness and the flexural strength decreased, and the fracture toughness increased. The Al ligament failed by ductile rapture and the AIN grains failed by transgranular fracture. The toughening mechanism of the composites mainly consisted in crack bridging and microcrack toughening.