In Situ Formation of Al₃Ti and Its Effects on the Microstructure, Hardness and Tribological Properties of Al Matrix Composites with Various Ti Contents

At present, Al matrix composites (AMCs) have drawn much attention owing to their light weight, high specific strength, high thermal conductivity, and superior excellent wear resistance, which endows them with great potential in the aerospace, automobile and military industries. In this study, AMCs with different Ti contents (0, 5 and 10 vol.%) were prepared by powder metallurgy. During the sintering, Al3Ti particles were in situ formed in the Al matrix. It was found that the Ti completely reacted with the Al matrix and formed fine in situ Al3Ti particles in Al-10Ti, while some large Ti-Al3Ti core-shell formed in Al-5Ti due to the incomplete reaction between the Ti and the Al matrix. Furthermore, the hardness of the composites was significantly improved by the in situ formed Al3Ti particles, reaching 143.3 HV in Al-5Ti and the highest value at 331.2 HV in Al-10Ti, respectively. The wear resistance of the composites is remarkably enhanced by Al3Ti particles compared to the unreinforced Al. Al-5Ti has the highest wear resistance among the samples. The wear resistance of the Al-10Ti composite becomes slightly deteriorated compared to Al-5Ti due to the brittle nature of Al3Ti, which leads to a three-body abrasive wear.