Dynamic Behavior and Constitutive Model for Two Tantalum-Tungsten Alloys under Elevated Strain Rates

The quasi-static and dynamic deformation behavior of two Ta-W alloys (Ta-2.5W and Ta-10W, mass fraction) was investigated by the quasi-static and dynamic compression test and Split Hopkinson pressure bar (SHPB) and Taylor impact tests. The results show that the yield stress of Ta-W alloys exhibits sensitivity to strain rate and W content. Based on the quasi-static and high strain-rate experimental data, the material constants in Johnson-Cook (JC) model were obtained for the two Ta-W alloys. In addition, validation of the derived constitutive model was carried out through comparison of Taylor impact inhomogeneous deformations under high strain rate (103∼104 s−1), obtained from simulations with their experimental counterparts. It is shown that the simulation results agree well with post-test geometries in terms of side profiles and impact-interface footprints for Taylor impact tests. To bridge the different spatial scale involved in the process of tantalum-tungsten alloy deformation, a meso-scale research was proposed via optical microscope (OM) image analysis. The results presented in this paper, provide new insights into the mechanisms suitable for the constitutive relations determination process.