Evolution of microstructure and texture during thermo-mechanical processing of a two phase Al0.5CoCrFeMnNi high entropy alloy

The evolution of microstructure and texture during thermo-mechanical processing of two phase (FCC + BCC) Al0.5CoCrFeMnNi was investigated. For this purpose, the fully recrystallized starting material having 17% of the BCC phase was warm-rolled to 75% reduction in thickness and annealed at temperatures ranging from 1000 degrees C to 1250 degrees C. The volume fractions of the two phases remained unaltered during warm-rolling. Development of a lamellar deformation structure was observed for the FCC phase which also showed presence of typical deformation components. In contrast, the BCC phase showed mechanical fragmentation indicating limited ductility and a deformation texture characterized by RD (//< 110 >) and ND (//< 111 >) fibers. Development of a finer recrystallized microstructure was observed after annealing at 1000 degrees C due to the grain boundary pinning exerted by the BCC phase, thus inhibiting grain growth. The BCC phase fraction decreased consistently with increasing annealing temperature. Considerable grain growth happened after annealing at 1250 degrees C due to the decrease in the BCC fraction, which greatly diminished the grain boundary pinning. The BCC phase also showed stronger ND-fiber in the primary recrystallization texture, which weakened with increasing annealing temperature due to the dissolution of this phase. Retention of the deformation texture components in the recrystallization texture of the FCC phase indicated absence of strong preferential nucleation or growth