Evolution of microstructure and mechanical properties during annealing of rolled CoFeMnNi-5Cr-5Al-1C alloy

Abstract

The evolution of microstructure and mechanical properties during annealing has been studied in a 90% rolled CoFeMnNi-5Cr-5Al-1C multi-principal element alloy. The rolled microstructure is observed to be strongly heterogeneous, comprising twinned regions and shear bands, layers of mixed orientations with high frequencies of high-angle boundaries, and extended regions dominated by low-angle boundaries. During annealing at 800 °C, shear bands and layers of mixed orientations act as preferential sites both for nucleation of recrystallized grains and for precipitation of B2 and carbide particles. Tensile tests conducted at room temperature reveal high yield strength (∼800 MPa) and good uniform elongation (14% and 17%) in partially recrystallized samples obtained by annealing for 30 min and 1 h.