Quasi‐Linear Superelasticity with Ultralow Modulus in Tensile Cyclic Deformed TiNi Strain Glass

Abstract

Herein, a quasi‐linear superelasticity (≈2.3%) with the ultralow elastic modulus (≈18 GPa) over a wide temperature range (≈55 K) in tensile cyclic deformed TiNi shape memory alloys is reported. Differential scanning analysis (DSC) and dynamic mechanical analysis (DMA) show the suppression of normal martensitic transformation (MT) and the appearance of strain glass transition behavior. Electron backscatter diffraction (EBSD) analysis shows the existence of high‐density defects involving twin boundaries and dislocations under tensile cyclic deformation. Further transmission electron microscope (TEM) observation reveals stabilized B19' nanodomains after tensile cyclic deformation. The observed deformation defects and stabilized B19' nanodomains impose significant influence on the following transition behavior and mechanical property, yielding the detected quasi‐linear superelasticity with ultralow modulus. Herein, an effective way to design unique phase transitions with unprecedented properties by defect engineering may be suggested.