颗粒形貌及热处理对SiC_p/2024Al复合材料性能的影响

采用粉末半固态触变成形工艺制备了SiCp体积分数为60%的2024Al复合材料。研究了SiCp形貌及热处理对复合材料性能的影响。结果表明,经表面整形的SiCp制备的复合材料增强体颗粒均匀弥散地分布在铝基体上,其致密度能达到99.97%。对复合材料进行去应力退火和T6热处理后,复合材料得到最佳综合性能,其抗弯强度和硬度得到明显提高,与复合材料热处理前相比,分别提高了47.5%和57.7%。复合材料的断裂整体表现为SiCp的解理断裂,基体呈现出撕裂。对SiCp整形和复合材料退火及T6热处理后降低了复合材料的热膨胀系数,分别达到(4.85~8.51)×10^-6、(4.86~8.32)×10^-6℃^-1。经改进后的H-J模型可以更好地适用于混合增强和双峰粒径分布的情况。对SiCp整形和复合材料退火及T6热处理后显著提高了复合材料的热导率,分别达到195、206W·m^-1·K^-1。

Effects of Particle Morphology and Heat Treatment on Properties of SiC_p/2024Al Composites

SiCp/2024 aluminum matrix composites with a volumetric fraction of 60%SiCp were prepared using a powder semi-solid thixoforming process.The effects of SiCp article morphology and heat treatment on the properties of the composites prepared were investigated.The results reveal that the composite reinforcement particles prepared by surface-shaped SiCp articles are uniformly dispersed in the aluminum matrix,and the relative density can reach 99.97%.After the stress relief annealing and T6 heat treatment,the composites present the desirable comprehensive performance,and the flexural strength and hardness of the composites are obviously improved,which is 47.5%and 57.7%higher than those of ones before heat treatment.The fracture of the composites exhibits a cleavage fracture of SiC as a whole,and the matrix exhibits tearing behavior.After SiC particle shaping and composite annealing as well as T6 heat treatment,the CTE of the composites is reduced to(4.85~8.51)×10^-6℃^-1 and(4.86~8.32)×10^-6℃^-1,respectively.The improved H-J model is better suitable for mixed reinforcement and bimodal particle size distribution.After SiC particle shaping and composite annealing as well as T6 heat treatment,the TC of the composites is significantly improved,reaching 195 W·m^-1·K^-1 and 206 W·m^-1·K^-1,respectively.