Local chemical fluctuation mediated ultra-sluggish martensitic transformation in high-entropy intermetallics
Yuan Wu, Fei Zhang, Fengshou Li, Yi Yang, Jiaming Zhu, Hong‐Hui Wu, Yao Zhang, Rui Qu, Zhefeng Zhang, Zhihua Nie, Yang Ren, Yandong Wang, Xiongjun Liu, Hui Wang, Zhaoping Lü
Abstract
high-entropy intermetallics (HEIs) show superelasticity with high critical stress over 500 MPa, high fracture strength of over 2700 MPa, and small temperature sensitivity in a wide range of temperatures over 220 K. The complex sublattice occupation in these HEIs facilitates formation of nano-scaled local chemical fluctuation and then elastic confinement, which leads to an ultra-sluggish martensitic transformation. The thermal activation of the martensitic transformation was fully suppressed while the stress activation is severely retarded with an enhanced threshold stress over a wide temperature range. Moreover, the high configurational entropy also results in a small entropy change during phase transformation, consequently giving rise to the low temperature sensitivity of the superelasticity stress. Our findings may provide a new paradigm for the development of advanced superelastic alloys, and shed new insights into understanding of martensitic transformation in general.