细晶93W-4.9Ni-2.1Fe合金动态压缩下绝热剪切带的形成及其特征

Formation and Characteristics of Adiabatic Shear Band in Fine-Grained 93W-4.9Ni-2.1Fe Alloy under Dynamic Compression

摘要:

利用分离式Hopkinson动态压缩装置对添加0.03%Y2O3(质量分数, 下同)的细晶93W-4.9Ni-2.1Fe合金试样进行动态力学性能测试，观察分析了动态压缩后合金试样的显微组织。结果表明：在应变速率为1900 s-1下，合金沿着与冲击方向成45o的方向形成了明显的绝热剪切带，宽度10~25 μm。说明该合金对局部绝热剪切的敏感性大大提高且能在相对较低的应变速率下发生绝热剪切。同时位于剪切带中心区域的钨颗粒沿着其扩展方向被剧烈拉长成纤维状，表现出塑性流动局域失稳的特征

Abstract:

he dynamic mechanical properties of fine-grained tungsten heavy alloy 93W-4.9Ni-2.1Fe with trace yttria addition were investigated under dynamic compression using Split Hopkinson Pressure Bar. The microstructure of the alloy sample after dynamic compression was analyzed. The results reveal that two obvious adiabatic shear bands were observed at the strain rate of 1900 s-1, indicating that the susceptibility of the fine-grained alloy to local adiabatic shear is significantly enhanced and the fine-grained alloy can form the shear bands at a lower strain rate. The adiabatic shear bands initiate in the crack tip region of the surface area of the specimen, propagating deeply along orientations at 45o to the impact direction. The bands have much narrower width of about 10-25 mm than that of traditional tungsten heavy alloy. Within the center of the bands, the tungsten grains are severely elongated to be fibrous along the propagation directions of the adiabatic shear bands, exhibiting plastic flow localized instability