摘要
采用等温热处理法制备了Mg-7Zn-0.3La-xCu(x=0,0.5,1.0,1.5,质量分数,％,下同)镁合金半固态浆料.利用光学显微镜、扫描电镜和EDS等设备观察Cu含量、等温温度和等温时间对Mg-7Zn-0.3La镁合金半固态组织演变的影响.结果显示,Mg-7Zn-0.3La-1Cu镁合金的铸态组织组成主要由白色α-Mg基体和黑色共晶组织(α-Mg+MgZn2+Mg4Zn7+CuMgZn)组成.该合金在等温热处理初始阶段,Cu起着加速非枝晶颗粒分离和球化的作用;随着等温温度的升高或等温时间的延长,非枝晶颗粒尺寸和形状因子呈先减小后增大的趋势,其中等温温度为580 ℃,等温时间为30 min时,Mg-7Zn-0.3La-1Cu镁合金的非枝晶组织呈现理想状态,此时的非枝晶颗粒的平均尺寸、形状因子和固相率分别为43.51 μm、1.32和64.38％.在半固态组织的演变过程中,合金组织主要经历了初始粗化、组织分离、球化及最后的粗化4个阶段.
Abstract
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.
基金项目
甘肃省科技重大专项资助项目(22ZD6GA008)
维普
万方数据