Aging behavior of high volume fraction SiCp/Al composites fabricated by pressureless infiltration

•The SiC/Al composite is prepared with 55% volume fraction of the SiC particle.•Pressureless-infiltration technology was employed to fabricate in the composite.•The TEM images of the phases have been used to analyze the age-hardening peaks.•The large amount of SiCp has changed the aging behavior of the composite.•The base alloy presents two aging peaks, while the composite presents one.

Aging behaviors of the high-volume-fraction SiCp/Al-Mg-Si composite fabricated by pressureless-infiltration and its base alloy at 170 °C were investigated in this study. The result indicates that the hardness of the composite is much higher and earlier to arrival to the peak-hardness than that of the base alloy. Al-Mg-Si alloy presents “double-peak phenomenon” in the aging treatment process, which can be attributed to the precipitation of the GP zones and the co-existence of the β″, β′ and Type C precipitates. The 55% SiCp/Al composite only presents one, which is due to the co-existence of the GP zone, β″, β′ and Type A precipitates. The maximum hardness increments of Al-Mg-Si alloy and the composite are 242% (4 h) and 22% (3 h) after aging treatment.