采用光学显微镜、扫描电镜、能谱仪和电子万能试验机等研究了复合添加稀土元素钕和铒的AZ91D镁合金显微组织和拉伸性能。结果表明: 在AZ91D合金中复合添加稀土钕和铒, 并经420 ℃×8 h固溶处理和165 ℃×10 h人工时效处理后, 合金组织明显被细化, 形成大量的颗粒状稀土化合物和沿晶界分布的析出相;当加入质量分数0.8%钕和0.4%铒时, 合金晶粒尺寸最小, 晶粒内弥散分布的析出相颗粒也最多, 沿晶界处形成了连续网络状的析出相, 此时合金的室温和高温抗拉强度都达到最高值, 分别为238 MPa和182 MPa, 比单独加入质量分数0.4%铒时分别提高了30%和21%。

Using the optical microscopy, scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and tensile tesing, the microstructure and tensile properties of AZ91D magnesium alloy compositely added rare earth Nd and Er were studied. The results show that the microstructure of AZ91D alloy was obviously refined, and a quantity of granular rare-earth compound in grains and precipitates along grain boundaries were formed after the alloy was compositely added rare earth Nd and Er and then was treated by 420 ℃×8 h solid solution and 165 ℃×10 h artificial aging. When 0.8wt.% Nd and 0.4wt.% Er were added into the AZ91D alloy, the grain size of the AZ91D alloy reached the minimum, the uniformly dispersed precipitates in the grains reached the most in quantity, the continuous network precipitates along grain boundaries were formed, the tensile strength of the alloy at room temperature and high temperature reached the maximum value, 238 MPa and 182 MPa, which were increased by 30% and 21% compared with the AZ91D alloy added 0.4wt.% Er only.