Effects of Zr on Microstructure and Properties of Hypoeutectic Al-Si-Cu-Ni-Mg Multi-element Alloy
Effects of Zr on solidification process,microstructure,mechanical properties and corrosion resistance of hypoeutectic Al-9.5Si-5Cu-2.5Ni-0.5Mg multi-alloy were investigated by direct-reading spectrometer,differential scanning calorimetry(DSC),field emission scanning electron microscope(SEM),universal testing machine and elec-trochemical workstation.The results indicate that Zr is trace doped in Al3CuNi phase,leading to Al3(CuSiZr)Ni phase.Zr doping hardly affects the phase structure,resulting in the morphology transformation from continuous network to discrete flaky,obviously reducing the overlap continuity and connectivity between the heat-resistant phases,which is the main reason that the room temperature and high temperature tensile strength are decreased with increasing Zr con-tent(Zr≤0.2％).In addition,Zr can reduce the corrosion potential of alloy,and the evolution of Al3CuNi phase mor-phology leads to incomplete oxide films during the corrosion process,which deteriorates the corrosion resistance of the alloy.Moreover,the corrosion resistance is worse with Zr content increasing.
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