Strengthening of ferrous medium entropy alloys by promoting phase transformation.

The design of medium-entropy alloys (MEAs) with low-cost and high-performance is a hot topic in the field of metal materials. Here, low amount of Co and Ni element is employed to prepare Fe–Co–Ni–Cr MEA, resulting in a reduced material cost of MEA, which also lead to low stacking fault energy and subsequently promote phase transformation in the alloy system. The achieved cost-effective Fe 65 Co 10 Ni 10 Cr 15 MEA has excellent cryogenic strength of 1.6 GPa and strain of 56%, which has the highest strength-price ratio among the reported MEAs so far. The significant strengthening of the alloy is attributed to the hetero-deformation and the accelerated deformation-induced phase transformation. • Microstructure and mechanical properties of novel Fe 65 Co 10 Ni 10 Cr 15 MEA was studied. • The alloy shows a well combination of strength and ductility both at 293 K and 77 K. • Hetero-deformation and TRIP effect are the main strengthening mechanism. [ABSTRACT FROM AUTHOR]