Creating heterogeneous lamella structure in a multiphase Al-Cr-Fe-Co-Ni complex concentrated alloy

The present work reports strength-ductility synergy achieved in an Al–Cr–Fe–Co–Ni complex concentrated alloy (CCA) through utilizing the heterogeneous lamella (HL) structure produced by a simple two-step thermo-mechanical processing route (cold rolling + annealing). The as-cast microstructure consists of dendritic FCC phase and inter-dendritic BCC phase having coherent precipitation of B2 particles. Compared to the as-cast specimen, nearly all the processed materials in this study showed significant simultaneous enhancement in both strength and ductility, which has not been achieved previously on CCAs with this type of microstructure. In addition, their mechanical properties can be tuned by changing the annealing time and resulted in superior properties compared to other CCAs of similar phase constitution. Moreover, the multiphase HL structure also exhibited a stronger Bauschinger effect compared to other HL-structured materials with heterogeneity among the lamellae generated solely by grain size difference. The strategy demonstrated in this work provides a cost-efficient and less composition-dependent direction for fabricating high-performance structural materials.