Structure and Performance Changes of Ni-Co-Al Shape Memory Alloys in Relation to Co/Al Atomic Ratio

作     者：Jia JU Feng XUE Liu-xia SUN 

作者机构：School of Materials Science and EngineeringSoutheast University 

出 版 物：《Journal of Iron and Steel Research International》 (J. Iron Steel Res. Int.)

年 卷 期：2015年第22卷第7期

页      面：652-656页

核心收录：

学科分类：08[工学] 080502[工学-材料学] 0805[工学-材料科学与工程（可授工学、理学学位）] 

主　　题：microstructure Co/Al atomic ratio martensitic transformation magnetic property Ni-Co-Al 

摘      要：As a potential ferromagnetic shape memory alloy, Ni-Co-Al has excellent mechanical properties, large ma gentic-field-induced strain and high martensitic transformation temperature. The relationship between microstructure and performance （mechanical and magnetic properties） of Ni-Co-Al with different Co/Al atomic ratios （RCo/Al） was investigated. Samples exhibit β and γ dual-phase structure. The γ phase grows coarse and the volume fraction of γ phase increases with the rise of RCo/Al. Besides, sample with high amount of γ phase content has smaller βgrains ow- ing to the pinning effect of γ phase. The martensite, transformed from β phase, is tetragonal L10 structure with a （111） twinning plane. The martensitic transformation temperature of samples ascends with increasing R co/Al owing to more Co embedded into the cell, which makes the valence electron concentration （e/a） of system rise. The satura- tion magnetization （Ms） of samples increases as Rco/Al rises because Co-rich 7 phase has excellent magnetic property. Meanwhile, both compressive and micro-hardness tests reveal that the samples containing more γ phase have excel- lent ductility due to the intrinsic good ductility nature of γ phase.