高应变率下细晶W-Ni-Fe合金的力学行为与局部绝热剪切带的形成

Dynamic Behavior and Adiabatic Shear Bands in Fine- Grained W-Ni-Fe Alloy under High Strain Rate Compression

摘要:

研究晶粒细化和添加微量稀土元素Y对93W-4.9Ni-2.1Fe合金在动态压缩状态下力学行为的影响，观察分析显微组织的变化。结果表明，93W-4.9Ni-2.1Fe合金在高应变率加载下会出现应变硬化和热软化现象，合金强度和延性随着应变率的增大而增加；与传统W-Ni-Fe合金相比，细晶W-Ni-Fe合金在高应变率下具有更高的合金强度和延性，同时能在较低应变率下形成明显的局部绝热剪切带。表明细化晶粒能提高W-Ni-Fe合金的强度以及绝热剪切敏感性；另外，添加微量稀土元素Y能提高W-Ni-Fe合金在高应变率下的强度和延性，并且在低应变率下发生绝热剪切，稀土元素Y的添加有利于绝热剪切带的形成。

Abstract:

The effect of grain refinement and trace yttrium addition on dynamic behavior of 93W-4.9Ni-2.1Fe alloy was investigated. The true stress-strain curves obtained from dynamic compression tests show that strain hardening and thermal softening effects are present in the alloy, and the maximum dynamic strength and elongation increase with increasing of strain rates. Compared with the conventional 93W-4.9Ni-2.1Fe alloy, the fine-grained 93W-4.9Ni-2.1Fe alloy exhibits relatively higher strength and elongation under the same compression condition. In particular, the occurrence of obvious adiabatic shear bands in fine-grained alloy under lower high-strain-rate (1900 s-1) indicates that the propensity to adiabatic shear localization are enhanced significantly by grain refinement. Additionally, trace yttrium addition can improve the dynamic strength and elongation of tungsten heavy alloy.