AGING CHARACTERISTICS OF A HIGH VOLUME FRACTION SiC_P/LD2 COMPOSITE

A 40 vol%SiC_P/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 SiC_P/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.