The mechanical behavior and microstructural evolution of a dual-phase 90W-7Ni-3Fe alloy under quasi-static and dynamic loading

The present work investigates the mechanical behavior and microstructural evolution mechanisms under quasi-static and dynamic loading in a dual-phase 90W-7Ni-3Fe alloy. Interrupted compressed tests are performed at strain rates of 0.01 and 6000 s- 1. The results show positive strain-rate sensitivity on the yield strength is available for 90W-7Ni-3Fe alloy, and the strain hardening effect weakens with increasing the strain rates due to the adiabatic environment upon dynamic loadings. Under quasi-static loading, the dislocation structure in the W particles and the deformation twinning in the gamma-(Ni, Fe) phase continued to increase during deformation, resulting in the alloy exhibiting significant strain hardening over a long period of time. While thermal softening effect dominates during plastic flow upon dynamic loading. With increasing deformation, the temperature in-crease can accelerate dislocation realignment and annihilation in both two phase, resulting in the formation of a dislocation substructure. In addition, the orientation relationship between the W/gamma-(Ni, Fe) interface is defined as Kurdjumov-Sachs, which facilitates the dislocation slip transfer from the gamma-(Ni, Fe) phase to the W particles and completes the plastic co-deformation of the 90W-7Ni-3Fe alloy. These results not only advance the under-standing of the deformation mechanisms in tungsten heavy alloys under different application environment but also offer the design of tungsten alloys should pay more attention to the dual-phase interface structure.

Automated summary

This study investigates the mechanical behavior and microstructural evolution mechanisms of a dual-phase 90W-7Ni-3Fe alloy under quasi-static and dynamic loading. The results show that the yield strength of the alloy is sensitive to strain rate, with a weakening strain hardening effect at higher strain rates due to the adiabatic environment during dynamic loadings. Quasi-static loading leads to the increase of dislocation structure in W particles and deformation twinning in the gamma-(Ni, Fe) phase, resulting in significant strain hardening. On the other hand, thermal softening dominates during plastic flow under dynamic loading.