Effects of Ni content on microstructure and wear behavior of Al–13Si–3Cu–1Mg-xNi-0.6Fe-0.6Mn alloys

As one of the lightweight and wear-resistance metallic structural materials, cast Al–Si alloys have been widely studied in automobile and defense industries to meet the greater demands for elevated-temperature wear-resistance properties. In this study, the effect of Ni content on the microstructure and wear behavior of Al–13Si–3Cu–1Mg-xNi-0.6Fe-0.6Mn alloys were investigated by thermodynamic modeling, X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) and ball-on-disk reciprocating sliding test. The results show that the θ-Al₂Cu and γ-Al₇Cu₄Ni phases are disappeared, while the δ-Al₃CuNi, ε-Al₃Ni, and T-Fe phases are formed with the increasing of Ni contents. The 3-D network structure is composed of α-Al matrix, eutectic Si, Q, Ni-rich, and Al₁₅(Mn, Fe)₃Si₂ phases, which leads to the best hardness and wear-resistance of the alloy with 2 wt% Ni. The fracture and debonding of excessive coarse ε-Al₃Ni phase deteriorate the wear-resistance and ductility of the 3Ni alloy. The main wear mechanisms of the tested alloys are abrasive, delamination and oxidative wear at 25 °C and convert to adhesive wear at 350 °C.