A strategy for Triple-TRIP-induced ultra-high room-temperature ductility of high-entropy alloys

Metastable dual-phase HEAs with fine-grain structure exhibit the B-TRIP effect during room-temperature tensile testing, with a maximum elongation at a break of 77 %. This paper adopts three strategies: SFE calculation, fine grain structure preparation, and phase ratio control, to design and prepare a new Fe₄₉Mn_33.2Cr_9.6Co_8.2 HEA that can achieve multiple interconversion conditions between FCC and HCP phases thermodynamically in order to fully leverage the synergistic effect of SFE phase composition and stability grain size on room-temperature ductility. The results showed that the alloy did not fracture after undergoing the B-TRIP effect but underwent FCC phase to HCP phase transformation again at a deformation of 70 % until the fracture process. At the time of fracture, the HCP phase content remained at around 40 %, and the alloy exhibited a particular five-stage strain-hardening behavior. Under the Triple-TRIP effect, the highest post-fracture elongation at room temperature reported so far was obtained, which was 91 %.