A polymer-like ultrahigh-strength metal alloy

• 成果类型: Article
• 署名作者: Xu, Zhizhi; Ji, Yuanchao; Liu, Chang; He, Liqiang; Zhao, Hui; Yuan, Ye; Qian, Yu; Cui, Jin; Xiao, Andong; Wang, Wenjia; Yang, Yang; Ma, Tianyu; Ren, Xiaobing
• 署名单位: Xi'an Jiaotong University; Xi'an Jiaotong University; Xihua University; Chinese Academy of Sciences; Institute of Physics, CAS; National Institute for Materials Science
• 刊物名称: Nature
• ISSN/ISSBN: 0028-5779
• DOI: 10.1038/s41586-024-07900-4
• 发表日期: 2024-09-19
• 页码: 575-581
• 关键词: shape-memory alloy; martensitic-transformation; strain; superelasticity; precipitation; deformation; hysteresis

摘要

Futuristic technologies such as morphing aircrafts and super-strong artificial muscles depend on metal alloys being as strong as ultrahigh-strength steel yet as flexible as a polymer1-3. However, achieving such 'strong yet flexible' alloys has proven challenging4-9 because of the inevitable trade-off between strength and flexibility5,8,10. Here we report a Ti-50.8 at.% Ni strain glass alloy showing a combination of ultrahigh yield strength of sigma y approximate to 1.8 GPa and polymer-like ultralow elastic modulus of E approximate to 10.5 GPa, together with super-large rubber-like elastic strain of approximately 8%. As a result, it possesses a high flexibility figure of merit of sigma y/E approximate to 0.17 compared with existing structural materials. In addition, it can maintain such properties over a wide temperature range of -80 degrees C to +80 degrees C and demonstrates excellent fatigue resistance at high strain. The alloy was fabricated by a simple three-step thermomechanical treatment that is scalable to industrial lines, which leads not only to ultrahigh strength because of deformation strengthening, but also to ultralow modulus by the formation of a unique 'dual-seed strain glass' microstructure, composed of a strain glass matrix embedded with a small number of aligned R and B19 ' martensite 'seeds'. In situ X-ray diffractometry shows that the polymer-like deformation behaviour of the alloy originates from a nucleation-free reversible transition between strain glass and R and B19 ' martensite during loading and unloading. This exotic alloy with the potential for mass producibility may open a new horizon for many futuristic technologies, such as morphing aerospace vehicles, superman-type artificial muscles and artificial organs. A polymer-like ultrahigh-strength TiNi alloy was fabricated by a simple three-step process to give a combination of a polymer-like ultralow elastic modulus and a steel-like ultrahigh yield strength over a wide temperature range, and such exotic properties arise from a unique strain glass state.