Significant Contribution to Strength Enhancement from Deformation Twins in Thermomechanically Processed Al 0.1 CoCrFeNi Microstructures

Strengthening mechanisms from thermomechanical processing treatments were explored in single-phase FCC high-entropy alloy Al0.1CoCrFeNi. Cold work offers substantial strengthening in this low stacking fault energy material owing to the resultant high work hardening rates. An enormous increase in yield strength of ~ 275% was obtained in 40% rolled material, but was accompanied by a steep drop in ductility. Recovery and recrystallization annealing treatments were investigated for improving elongation and obtaining better balance of strength–ductility combinations. Formation of novel microstructures from the different processing routes was examined. X-ray diffraction peak broadening and mechanical test results were coupled to estimate micro-strain in the different conditions and understand micro-strain’s correlation to strength. Retention of large-scale deformation twins formed during cold rolling is shown to play a key role in elevation of yield strength after heat treatments.