Phase transition of Ni_(55-x)Co_(x)Mn_(20)Ga_(25)(8.5≤x≤11.0)alloys with different compositions and magnetic fields  

作　　者：Xiao Wang Jing-Min Wang Hui Hua Cheng-Bao Jiang 

机构地区：[1]Key Laboratory of Aerospace Materials and Performance(Ministry of Education),School of Materials Science and Engineering,Beihang University,Beijing,100191,China

出　　处：《Rare Metals》2023年第2期572-578,共7页稀有金属（英文版）

基　　金：financially supported by the National Basic Research Program of China(No.2012CB619404);the National Natural Science Foundations of China(Nos.51221163,51331001);Beijing Natural Science Foundation(No.2132126);the Fundamental Research Funds for Central Universities。

摘　　要：Studies on Co-doped Ni–Mn–Ga ferromagnetic shape memory alloys(FSMAs)have been quite active topics in recent years.Unlike previous reports where the amount of Co doping was generally less than 8 at%,in this work Ni_(55-x)Co_(x)Mn_(20)Ga_(25)(8.5≤x≤11.0)alloys were studied with high Co doping.Unusual effects of both composition and magnetic field on phase transitions were observed.With the increase in substitution of Co for Ni,the magnetic transition temperatures increase gradually but the martensitic transformation temperature decreases quite sharply.In particular,the average decrease in the martensitic transformation temperatures is up to 100 K which is nearly twice that in the case of Co content of less than 8 at%.Further,under an applied magnetic field ranging from 0.03 to 0.60 T,abnormal stabilization of a martensite phase with lower magnetization was monitored.Magnetic entropy change of 1.6 J·kg^(−1)·K^(−1)was induced at the martensitic transformation of Ni46.5Co8.5Mn20Ga25 alloy by an applied field of 1 T.The magnetic contributions,including the magnetocrystalline anisotropy and the Zeeman energy,to the thermodynamics of the martensitic transformation are considered to understand the observed unusual phenomena.This work results in new insights into the understanding of Co-doped Ni–Mn-based ferromagnetic shape memory alloys.

关 键 词：NI-MN-GA Ferromagnetic shape memory alloys Martensitic transformation Magnetic properties Magnetocaloric effect 

分 类 号：TG139.6[一般工业技术—材料科学与工程]