摘要
真空感应熔炼法制备了多晶Ni52Mn24.4Ga23.6合金,利用粉末压缩压制的方法制备了粘结Ni52Mn24.4Ga23.6磁体。通过DSC,XRD,SEM等手段分析了多晶合金的组织形态、晶粒大小、马氏体转变温度及相变热滞后温度,讨论了外应力场和磁场对粘结Ni52Mn24.4Ga23.6磁体马氏体相变的影响。结果表明:该合金在18℃时发生热马氏体相变,生成5M马氏体;在粘结磁体的制备过程中,在内应力作用下,合金中的5M马氏体发生马氏体间相变,生成具有一定的择优取向的7M马氏体;应力诱发的7M马氏体在180℃保温3h后冷却到室温下时又回复为5M马氏体,但此时5M马氏体保留一定的择优取向;在应力诱发的7M马氏体形核和长大过程中施加外磁场,能进一步促进7M马氏体的择优生长。
Polycrystalline alloy Ni_(52)Mn_(24.4)Ga_(23.6) was prepared by repeated induction melting and bonded Ni_(52)Mn_(24.4)Ga_(23.6) magnets were prepared by powder compression method. The morphology, grain size, martensite transformation temperature and thermal hysteresis were investigated by means of DSC, XRD and SEM. The effects of external stress and magnetic field on martensitic transformation of bonded Ni_(52)Mn_(24.4)Ga_(23.6) magnets were discussed. The results show that a martensitic phase transition to 5M martensite occurs at 18 ℃ on cooling. When bonded magnet is compacted, internal stress will lead to the appearance of the intermartensitic transformation, and the corresponding sequence is from (5M) to 7M, which has some preferential orientations. When the stress-induced 7M martensite is annealed at 180 ℃ for 3 h, it will revert to (5M). But the preferential orientations of martensitic variants are kept to some extent. During the nucleating and growth of the stress-induced 7M martensite, external magnetic field will contribute to the nucleating and growth of favorable variants of 7M martensite.
出处
《中国稀土学报》
CAS
CSCD
北大核心
2005年第2期204-209,共6页
Journal of the Chinese Society of Rare Earths
基金
湖南省自然科学基金资助项目(02JJY2082)
