Dynamic failure and adiabatic shearbands in fine-grain 93W-4.9Ni-2.1Fe alloy with Y₂O₃ addition under lower high-strain-rate (HSR) compression

In this paper, Y₂O₃ dispersed 93W-4.9Ni-2.1Fe alloy with fine grains (FG) of about 3-5 μm has been fabricated by liquid-phase sintering of their respective nanocomposite powders. The dynamic properties of FG-WHA have been investigated under uniaxial dynamic compression using Split Hopkinson Pressure Bar. The results show that the FG-WHA exhibits an almost ideal elastic-plastic behavior with no work hardening and susceptibility of the adiabatic shear localization at lower strain rates than the traditional WHA. Two obvious adiabatic shearbands have been observed at the strain rate of 1900 s^-1. The adiabatic shearbands origins in the crack tip region in the surface area of the specimen, propagating deeply into the specimen along orientations at 45° to the impact direction. The bands have much narrower width of about 10-25 μm than that for traditional WHA (the width of bands is about 200 μm according to Kim et al. (1998a,b)). Within the center of the bands, the tungsten grains are severely elongated to be fibrous and orient along the propagation directions of the adiabatic shear bands, exhibiting plastic flow localized instability.