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

The current study reports the analysis of the deformation mechanisms at 600 degrees 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. (C) 2022 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Automated summary

This study analyzes the deformation mechanisms in a two-phase refractory complex concentrated alloy (RCCA) Al0.5NbTa0.8Ti1.5V0.2Zr at 600 degrees C. The alloy exhibits dynamic coarsening of B2 precipitates during mechanical testing and highly localized deformation in wavy bands after a true plastic strain of 0.030. Scanning transmission electron microscopy reveals the presence of paired a/2 <111> dislocations that shear the B2 precipitates cooperatively. Chemical segregation effect is also observed along narrow dislocation bands, possibly to reduce the antiphase boundary energy of the system.