高体积分数挤压铸造铝基复合材料时效特征

采用挤压铸造法制备40 ％SiC_P/LD2复合材料,并对其在不同温度下的时效特征进行了研究。结果表明,高体积分数SiC颗粒的加入带来的弥散强化作用,可以大幅度提高基体合金的硬度和强度,但区别于基体合金和低体积分数复合材料,复合材料本身时效强化效果不明显。高体积分数复合材料峰时效时间较低体积分数缩短,且随时效温度的提高峰时效时间缩短。低温时效时峰值硬度最高且时效动力学较基体合金提前幅度较大。在时效析出过程中,高体积分数复合材料G.P.区的形成受到完全抑制,而β'相热扩散激活能降低,易于析出。 

AGING CHARACTERISTICS OF A HIGH VOLUME FRACTION SiCP/LD2 COMPOSITE

A 40 vol%SiCP/LD2 composite was fabricated by squeeze casting, and the effect of high volume fraction SiC particulates on aging characteristics at different aging temperatures was studied.The results show that the rengthening effect due to the addition of particles plays the leading role and aging strengthening is not the major strengthening mechanism for the high volume fraction SiCP/LD2 composite. With the increasing of temperature the precipitation processes become accelerated, and the time to reach the peak hardness is shortened. Comparatively, at low aging temperature the peak hardness of composite is the highest and the aging process is more accelerated than that of LD2 alloy. The formation of G.P. region is severely suppressed and the thermal diffusion activation energy of β' phase is decreased due to the addition of SiC particles, which causes the precipitation of β' phase easier and the precipitation temperature range wider than that of LD2 alloy.