Exploiting ultra-large linear elasticity over a wide temperature range in nanocrystalline NiTi alloy

Zhen Sun¹，Shijie Hao^1,2，Genfa Kang¹，Yang Ren³，Junpeng Liu⁴，Ying Yang¹，Xiangguang Kong¹，Bo Feng¹，Cheng Wang¹，Kun Zhao¹，Lishan Cui¹

1. State Key Laboratory of Heavy Oil Processing, China University of Petroleum2. Beijing Key Laboratory of Failure, Corrosion, and Protection of Oil/Gas Facilities, China University of Petroleum Beijing3. X-ray Science Division, Argonne National Laboratory4. State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences

摘 要：Many shape memory alloys can support large recoverable strains of a few percent by reversible stressinduced martensite transformation,yet they behave non-linear within a narrow operating temperature ra nge.Developing the bulk metallic materials with ultra-large linear elasticity over a wide tempe rature range has proven to be difficult.In this work,a material design concept was proposed,that is true elastic deformation and reversible twinning-detwinning deformation run in parallel to overcome this challe nge.By engineering the residual internal stress to realize the concurrency of true elastic deformation and twinning-detwinning deformation,a bulk nanocrystalline NiTi that possesses an ultra-large linear elastic strain up to 5.1 % and a high yield stress of 2.16 GPa over a wide temperature range of 270℃ was developed.This study offers a new avenue for developing the metallic materials with ultra-large linear elasticity over a wide temperature range of 270℃（from 70℃ to-197℃）.

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