固溶和时效处理对铸造Mg-7.5Gd-3Y-0.5Zr合金动态冲击行为的影响

本研究采用金相观察、扫描电镜观察、能谱分析、X射线衍射、硬度测试以及分离式霍普金森压杆等手段，探究了经固溶和时效处理后Mg-7.5Gd-3Y-0.5Zr合金在室温条件下的动态冲击行为。结果表明：固溶态和时效态合金均表现出优异的抗冲击性能，固溶态合金在应变速率为3649s-1时合金抗压强度最高为507MPa；时效处理的合金，在4079s-1高应变速率下表现出了574.5MPa超高的抗压强度。固溶态合金随着应变速率的增加，动态析出相明显增多，合金性能明显提升，动态析出粒子与方块状富稀土粒子协调作用阻碍了位错运动，使合金保持优良的抗冲击性能。较固溶态合金而言，时效态合金动态析出相体积分数减少，随着应变速率的增大，动态析出也呈现减少的趋势，在高应变速率4079s-1时未观察到动态析出粒子。因此，时效态样品在变形过程中，纳米析出相是影响合金性能的主要因素，随着应变速率的增加，纳米析出相作用更加突出。

The effect of solid solution and aging heat treatment on the dynamic impact behavior of cast Mg-7.5Gd-3Y-0.5Zr alloy

In this study, the dynamic impact behavior of the casting solid-solution and peak-aged Mg-7.5Gd-3Y-0.5Zr alloys at room temperature were investigated using optical microscopy(OM), scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS), X-ray diffraction(XRD), hardness testing and split Hopkinson pressure bar(SHPB). Our experiment confirmed that both the solid-solution and age-treated alloys have excellent impact resistance, and the highest compressive strength of the solid-solution alloy is 507 MPa at a strain rate of 3649 s-1. The age-treated alloy exhibited an ultra-high compressive strength of 574.5 MPa with high strain rate of 4079s-1. The dynamic precipitation phase increases significantly with the increase of strain rate in the solid solution alloy, and the alloy properties are significantly improved. The coordinated action of the dynamically precipitated particles and massive rich rare-earth particles hinders the dislocation movement, so that the alloy maintains excellent impact resistance. Compared with the solid solution alloy, the volume fraction of dynamic precipitation phase decreased in the aging alloy, and the trend of dynamic precipitation decreased with increasing strain rate, and no dynamic precipitation particles were observed at a high strain rate of 4079s-1. Therefore, the nano-precipitation phase is the main factor affecting the alloy properties during the deformation of the ageing state samples, and the role of the nano-precipitation phase becomes more prominent as the strain rate increases.