Mechanism of Ceramic-Like Friction of Quasicrystal-Reinforced Al Matrix Composites Formed by In Situ Directed Energy Deposition

Abstract The wear of aluminum alloy may be decreased by its reinforcement with quasicrystals (QCs) prepared by melt, which in itself has good wear-resisting properties. This research paper considers the part played by a dense Al-Fe-Cr QC reinforced Al matrix composite fabricated by the directed energy deposition (DED) in reducing wear between sliding surfaces and discusses briefly some of the factors which, in practice, explain ceramic-like properties of quasicrystal including low friction and wear resistance. The hardness of reinforcement phases, QC Al91Fe4Cr5 and Al13(Fe, Cr)4, was up to ∼91 and ∼112 HV respectively, while the Al matrix was just ∼70 HV. Furthermore, the reinforcement phases contributed to form the mechanical mixing layer (MML) which significantly decreased the coefficient of friction (COF) and improves the wear resistance. With the increase of load from 1 N to 5 N, the COF dropped from 0.82 to 0.33 because the higher load was beneficial to the formation of harder and denser MML. Through the comprehensive analysis of the wear test and worn surface, the wear behavior and mechanism of this QC-reinforced Al matrix composite have been explained in detail. The results indicate that the quasicrystal-reinforced Al matrix composites formed by DED are one of the promising wear-resistance materials.