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) Al _0.5NbTa _0.8Ti _1.5V _0.2 Zr. 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.