Resolution of a discrepancy of magnetic mechanism for Elinvar anomaly in Fe-Ni based alloys

作     者：Fangyu Qin Wenlong Xiao Fengshuang Lu Yuanchao Ji Xinqing Zhao Xiaobing Ren 

作者机构：School of Materials Science and Engineering Beihang University Functional Materials Research Institute Central Iron and Steel Research Institute Multi-Disciplinary Materials Research Center Frontier Institute of Science and Technology Xi'an Jiaotong University 

出 版 物：《Journal of Materials Science & Technology》 (材料科学技术（英文版）)

年 卷 期：2019年第35卷第3期

页      面：396-401页

核心收录：

学科分类：08[工学] 0817[工学-化学工程与技术] 0806[工学-冶金工程] 0805[工学-材料科学与工程（可授工学、理学学位）] 080502[工学-材料学] 0703[理学-化学] 0802[工学-机械工程] 0801[工学-力学（可授工学、理学学位）] 0702[理学-物理学] 

基　　金：supported financially by the National Natural Science Foundation of China (Nos. 51431007  51831006 and 51771012) 

主　　题：Fe-Ni based alloys Elastic modulus Magnetism Strain glass transition Nanodomains 

摘      要：Fe-Ni based Elinvar alloys performing temperature-independent elastic modulus over a wide temperature range have found wide and significant applications. Although numerous models involved with magnetism have been proposed to explain the Elinvar anomaly, some of the puzzles concerning the anomaly have not been fully understood. In this work, a remarkable discrepancy between the inflection temperature of modulus and the Curie temperature in a typical Fe-Ni-Cr Elinvar alloy was found,challenging the magnetic mechanism for Elinvar anomaly. Microstructural characterization and dynamic mechanical analysis demonstrate the occurrence of a strain glass transition with continuous formation of nanodomains. Accompanying such a transition, the gradual softening in the elastic modulus of austenite offsets the modulus hardening due to the vibrational anharmonicity of nanodomains upon cooling, leading to the Elinvar effect. As a result, the inflection temperature of modulus corresponds to the initiation of nanodomains formation instead of magnetic transition. Our findings specify the association of Elinvar anomaly with structural aspects, and provide new insights into the mechanism of Elinvar anomaly in Fe-Ni based alloy.