变形条件对Mg-Gd-Y-Nd-Zr合金动态力学行为的影响

Effect of Deformation Conditions on the Dynamic Mechanical Behaviour of Mg-Gd-Y-Nd-Zr Alloys

采用金相观察、扫描电子显微镜、能谱分析、显微硬度计及分离式霍普金森压杆等手段,研究了峰值时效挤压态Mg-8Gd-3Y-0.5Nd-0.5Zr合金在变形温度及应变速率下的动态冲击力学变形行为。结果表明:合金在220℃/14 h到达峰值时效,其硬度约为143.2 HV,提升了55%左右。在不同的变形温度下均表现出优异的抗冲击性能,在室温及应变速率为3000 s^(-1)条件下合金抗压强度可高达682 MPa;在100℃及应变速率为1500 s^(-1)条件下抗压强度为635 MPa;在400℃及应变速率为3000 s^(-1)条件下抗压强度为583 MPa。合金在不同温度下优异的抗冲击性能主要得益于时效强化相、稳定存在的块状富稀土粒子以及冲击过程中在晶界形成的动态析出相协同强化机制。随着应变速率和变形温度的增大,合金热软化效应增强,合金力学性能有所降低。

The dynamic impact mechanical deformation behavior of the Mg-8Gd-3Y-0.5Nd-0.5Zr alloy in its peak aging extruded state at deformation temperature and strain rate was investigated by means of observation metallographic(OM),scanning electron microscopy(SEM),energy dispersive spectrum(EDS),microhardness testers,and a split Hopkinson pressure bar(SHPB)methods.The results show that the alloy reaches peak aging at 220℃/14 h and its hardness is about 143.2 HV,which is an improvement of about 55%.The alloys show excellent impact resistance at different deformation temperatures,with compressive strengths of up to 682 MPa at room temperature and a strain rate of 3000 s^(-1);635 MPa at 100℃and a strain rate of 1500 s^(-1);and 583 MPa at 400℃and a strain rate of 3000 s^(-1).The excellent impact resistance of the alloys at different temperatures is mainly due to the synergistic strengthening mechanism of the age-strengthened phases,the stabilized massive rare-earth-rich(REH)particles,and the dynamic precipitation phases formed at grain boundaries during the impact process.As the strain rate and deformation temperature increase,the thermal softening effect of the alloy increases and the mechanical properties of the alloy decrease.