TRIP behavior of non-equiatomic Co40Cr20Ni15Fe15Mo10 high entropy alloys

Herein, the transformation-induced plasticity (TRIP) effect is investigated in a novel Co-rich high entropy alloy (HEA), Co40Cr20Ni15Fe15Mo10, by optimizing its constituent elements and processing conditions. The tensile properties of the HEA are shown to increase with strain rate, reaching a maximum tensile strength and elongation at a strain rate of 1 x 10-3 s- 1, due to the formation of martensite. The X-ray diffraction patterns reveal that the as-annealed HEA has initially a single FCC structure, but transforms a dual FCC and HCP structure at the above-mentioned strain rate, with the main deformation mechanisms being dislocation slip and phase transformation. The tensile fracture surface of the Co-rich HEA shows a stepped interphase boundary between the FCC and HCP phases, thus suggesting failure along the brittle HCP structure.