Mechanical response and failure behavior of BCC/FCC dual‐phase tungsten alloy during trans‐scale strain rate loading

Abstract The mechanical response and failure behavior of structural materials, particularly dual‐phase alloys, over wide strain rate ranges are key determinants of their service performance. This study taken the typical BCC/FCC dual‐phase 90W–7Ni–3Fe (wt%) alloy as an example. Using universal testing machines (UTM), split Hopkinson tensile bars (SHTB), laser shock (LS) loading, molecular dynamics (MD) simulations, and advanced characterization techniques, it systematically investigated the influence of deformation mechanisms on mechanical response and failure behavior under strain rates spanning 10 –3 –10 9 s −1 . At low/medium strain rates, deformation in both W particles and the γ phases was dominated by dislocation slip. At ultra‐high strain rates, W particles transitioned from dislocation slip to parallel {112} < 111 > nanotwins, while the γ phases shifted to parallel {111} < 112 > nanotwins, ultimately forming 70.52° rhombic intersecting nanotwins. The dual‐stage strength leap mechanism emerged, comprising dislocation density‐dominated continuous strengthening (10 –3 –10 3 s −1 ) and twin‐dominated abrupt strengthening (≥ 10 7 s −1 ). The fracture strength increased from 998.37 to 7466.51 MPa. The fracture mode underwent a transformation, with the formation of microcracks and the propagation of microcracks shifting from the W/γ interface to the interior of the W particles.