[SY-E5] Symposium E-5

[SY-E5] Computational Design of Hysteresis-Free and Linear Super-Elastic, and Ultralow Modulus Ferroelastic Materials

^○Jiaming Zhu¹, Yipeng Gao², Dong Wang³, Tong-Yi Zhang⁴, Yunzhi Wang² (1.City University of Hong Kong, Hong Kong, 2.Ohio State University, United States of America, 3.Xi'an Jiaotong University, China, 4.Shanghai University, China)

A unique characteristics of ferroelastic materials is their highly non-linear stress-strain curves with plateaus and large hysteresis. We show by computer simulations how to render ferroelastic materials nearly hysteresis-free and linear super-elastic (with an elastic strain limit of 2.7%), and ultralow modulus (<20 GPa) by creating appropriate concentration modulations (CMs) in the parent phase via spinodal decomposition and by pre-straining. The CM causes phase stability modulations, suppresses autocatalysis in nucleation, imposes nano-confinement on growth and hinders long-range order of transformation strain during martensitic transformation (MT) and, thus, turns the otherwise sharp first-order transition into a broadly smeared, macroscopically continuous transition over a large stress range. The pre-straining yields retained martensitic particles that are stable at the test temperature without applied load and act as operational nuclei in subsequent load cycles, eliminating the stress-strain hysteresis and offering an ultralow apparent Young’s modulus. This study demonstrates a novel and universal approach to design new ferroelastic materials with unprecedented properties.