Strain hardening rate and strain rate sensitivity behavior of bcc/fcc-dual-phase tungsten heavy alloy

Abstract

90W-7Ni-3Fe alloy is a heterogeneous biphasic alloy, and it is essential to investigate the impact of the biphasic microstructure on key mechanical properties at varying strain rates. To address this issue, the quasi-static and dynamic compressive mechanical properties of dual-phase 90W-7Ni-3Fe alloy, single-phase pure W, and single-phase NiFe alloy were comparatively analyzed in conjunction with characterization analysis. The results indicate that the flow stress, strain hardening rate (SHR), and strain rate sensitivity (SRS) of the 90W-7Ni-3Fe alloy at various strain rates are mainly due to the involvement of W particles during the initial strain, although the overall plastic deformation of the alloy is attributed to the continuous coordinated deformation of the W particles with γ-(Ni, Fe) phases in various regions. In addition, the compressed W phase shows a typical 〈111〉 and 〈100〉 BCC compression texture and the compressed γ-(Ni, Fe) phase shows a typical 〈110〉 FCC compression texture, both with high Schmidt factors. These characteristics are essential for slip transfer and strain transfer from the γ-(Ni, Fe) phase to the W phase. Notably, the increased number of slip systems at high strain rates makes them more susceptible to both types of transfer, resulting in higher flow stress, SHR, and SRS during initial deformation.