A unified constitutive model for quasi-static flow responses of pure Ta and Ta-W alloys

This study aims to develop a unified constitutive model describing the flow behaviors of pure Ta and Ta-W alloys over a wide range of strain rate and temperature. The model was based on the previously suggested model by Nemat-Nasser and Isaacs [3] and was further extended to capture the hardening effects caused by the changes in solute contents and concentrations, and grain size; while interstitial solutes (C, N, and O) increased the thermal stress, substitutional solute (W) increased both the thermal and athermal stresses. The results showed that the developed model can provide a reasonable prediction on the flow behaviors of pure Ta and Ta-W alloys (Ta-2.47W, Ta-5.2W, and Ta-9.8W) with different grain sizes of 0.3-45 μm over a strain rate range of 1-10⁻⁶ s⁻¹ and a temperature range of 77-900 K without any change in the material constants used.