Microstructure, tensile and wear properties of a novel graded Al matrix composite prepared by direct energy deposition

A novel graded Al matrix composite (AMC) was prepared by direct energy deposition (DED) from the mixture of pure Al, Cr and Fe powders. From the perspective of a single molten pool, the microstructure consists of two regions: AMC region with coarse Al₁₃Fe₄ laths and AMC region with fine Al₁₃Fe₄ particles. With increasing the deposited layer, the content of coarse Al₁₃Fe₄ lath decreases and the content of fine Al₁₃Fe₄ particle increases, which indicates the formation of a graded structure. Interestingly, the samples cut from different positions of graded AMC deposit exhibit the identical ultimate tensile strength (UTS, ∼222 MPa) except that the top region presents the higher ductility (3.8%) than the bottom region (1.1%). However, the bottom region presents the higher hardness (84.12 HV) and the better wear resistance than the top region. Moreover, this novel Al matrix composite prepared by DED exhibits favorable wear resistance compared to conventional cast Al-12Si alloy. This novel grade Al matrix composite possesses multifunctional properties of wear and tensile, which can be used as structural and anti-wear component in aerospace and automotive field.