Semi-solid Microstructure Evolution of Mg-7Zn-0.3La-xCu Magnesium Alloy
A Mg-7Zn-0.3La-xCu(x=0,0.5,1.0,1.5,％)magnesium alloy semisolid slurry was prepared using iso-thermal heat treatment method.The influence of Cu content,isothermal temperature,and isothermal time on the evo-lution of semi-solid microstructure of Mg-7Zn-0.3La magnesium alloy was observed using optical microscopy,scan-ning electron microscopy,and EDS analysis.The experimental results reveal that the as-cast microstructure of Mg-7Zn-0.3La-1Cu magnesium alloy mainly consists of a white α-Mg matrix and a black eutectic structure(α-Mg+MgZn2+Mg4Zn7+CuMgZn).During the initial stages of isothermal heat treatment,Cu plays a role in accelerating the sepa-ration and spheroidization of non-dendritic grains.With increasing in isothermal temperature or extension of isothermal time,the non-dendritic grain size and shape factor exhibit a trend of first decrease and then increase.Specifically,with the isothermal heat treatment parameters set at 580 ℃ for 30 min,the non-dendritic microstructure of Mg-7Zn-0.3La-1Cu magnesium alloy reaches desirable,where the average non-dendritic grain size,shape factor,and solid fraction reach up to 43.51 μm,1.32,and 64.38％,respectively.The evolution of semisolid microstructure mainly undergoes four stages:initial coarsening,structure separation,spheroidization,and final coarsening.
Cu ContentMagnesium AlloySemi-solidMicrostructure Evolution
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维普
