冲击载荷作用下Mg-Li合金的力学性能及显微组织

Mechanical Property and Microstructure of Mg-Li Alloys under High Strain Rate Impact Load

采用分离式霍普金森压杆(SHPB)对真空熔炼制备的Mg-Li合金进行了静、动态试验研究,试件的加载应变率范围为1.7×10-3～1026s-1,得到了材料在不同应变率下的应力-应变曲线。并根据实验结果确立了Mg-Li合金在一维应力高应变率冲击状态下的本构关系。同时还分析了不同应变率冲击后Mg-Li合金的金相组织。结果表明,该Mg-Li合金在室温下的动态冲击性能对应变率不敏感。Mg-Li合金在一维应力高应变率冲击状态下的本构关系为σ=1.5ε,(σ<0.12GPa),σ=0.12+2.7ε1.2(σ≥0.12GPa)。随着应变率的增加,晶粒尺寸先变小,再趋于不规则形状,而且晶界处分布的短条状化合物也逐渐集中。

The static and dynamic mechanical responses of Mg-Li alloy prepared by vacuum induction melting were investigated by split Hopkinson pressure bar （SHPB） under the strain rates of 1.7×10^-3-1026 s^-1, and the stress-strain curves under different strain rates were obtained. Based on the SHPB experimental results, the constitutive relation of this alloy under one-dimensional stress high strain rates impact was fitted. Besides, the metallurgical structure of the Mg-Li alloy after impact under different strain rates was also analyzed. Results show that the dynamic impact properties of the Mg-Li alloy are not sensitive to the strain rate. The constitutive relation of the Mg-Li alloy under one-dimensional stress high strain rates impact is σ=1.5c （σ〈0.12 GPa）, and σ=0.12＋2.7ε^1.2 （σ〉0.12 GPa）. With increase of the strain rate, the grains become smaller at first and then tend to be irregular shapes. The short-strip compounds are concentrated distributing in the boundaries.