High-temperature deformation mechanisms in a BCC+B2 refractory complex concentrated alloy

The current study reports the analysis of the deformation mechanisms at 600 °C in a two-phase, BCC+B2, refractory complex concentrated alloy (RCCA) Al0.5NbTa0.8Ti1.5V0.2Zr. At this temperature, the alloy microstructure is unstable and dynamic coarsening of B2 precipitates is evidenced during the mechanical testing. After true plastic strain of 0.030 at strain rate of 10−4 s−1, the deformation becomes highly localized in wavy bands reflecting the profusion of cross-slip. Scanning transmission electron microscopy (STEM) observations highlight the presence of paired a/2⟨111⟩ dislocations that shear the B2 precipitates in a cooperative process. In addition, some chemical segregation effect is observed along the narrow dislocation bands likely induced to decrease the antiphase boundary (APB) energy of the system. [Display omitted]