强磁场下Ni-Co-Mn-Sn合金近平衡凝固的组织调控  

Effect of a Strong Magnetic Field on the Microstructure of Near-equilibrium Solidified Ni-Co-Mn-Sn Metamagnetic Shape Memory Alloy

作　　者：翟强 卜凡[1,2] 马昌尧 刘子瑜 贺一轩 王军 李金山[2] ZHAI Qiang;BU Fan;MA Changyao;LIU Ziyu;HE Yixuan;WANG Jun;LI Jinshan(Center of Advanced Lubrication and Seal Materials,Northwestern Polytechnical University,Xi'an 710072,China;State Key Laboratory of Solidification Processing,Northwestern Polytechnical University,Xi'an 710072,China)

机构地区：[1]西北工业大学先进润滑与密封材料研究中心,陕西西安710072 [2]西北工业大学凝固技术国家重点实验室,陕西西安710072

出　　处：《铸造技术》2023年第5期426-433,共8页Foundry Technology

基　　金：国家自然科学基金(52104386);凝固技术国家重点实验室课题(2022-TS-08);陕西省留学人员科技活动择优资助项目。

摘　　要：利用先进材料处理技术持续优化Ni-Mn-Co-Sn记忆合金(Heusler合金)性能是智能材料领域的研究热点,其磁控记忆性能和机械性能的协同提升强烈依赖于合金凝固得到的微观结构。本文探究了磁场强度对Ni42Co8Mn39Sn11合金近平衡条件下凝固组织演变的影响规律。结果表明,在无磁场条件下,合金凝固组织主要由D03型粗大枝晶及L21枝晶间Heusler相组成,在枝晶间上还析出蠕虫状γ相,其中γ相富Co贫Sn,D03相富Sn贫Co,L21相的成分接近名义配比;D03结构由L21结构产生的成分偏析区域形成,析出γ相并非低温下L21相的固态反应得到。施加10 T强磁场后,合金的相组成、成分及其形貌未发生明显变化,各相间由于热流作用大于磁场引起的取向排列作用而未产生明显择优分布特征,但因偏析产生的D03相含量减少,L21相含量增加,这与强磁场促进Heusler相元素分布均匀化,减少偏析有关。Optimizing the overall performance of Heusler-type Ni-Mn-Co-Sn magnetic shape memory alloys(MSMA)by the application of advanced treatment technology in current smart material research has been a research hotspot.The properties of alloys are strongly related to the solidification microstructures.In this paper,the solidification microstructures of Ni42Co8Mn39Sn11 MSMA under different magnetic field intensities were studied.The results show that in the absence of magnetic field,the microstructure is mainly composed of D03 coarse dendrite trunks and L21 interdendrite,embedded with the vermicularγphase that is Co-rich and Sn-depleted,and the chemical composition of the D03 phase shows the opposite tendency.The D03 structure is formed due to the chemical segregation of the Heusler L21 phase,and theγphase is hardly obtained from the decomposition of the L21 phase in the range of 500~700℃.After the application of a 10 T high magnetic field,the phase constituent,chemical composition and morphologies of the alloy remain stable,and no obvious alignments or textures are found due to the enhanced thermal energy rather than the weakened anisotropic magnetic energy.In addition,the fraction of the D03 phase decreases efficiently,and the L21 phase rises when a magnetic field is applied,i.e.,a strong magnetic field could alleviate the chemical fluctuation and contribute to the formation of a more uniform distribution of Heusler phase elements.

关 键 词：强磁场 Ni-Co-Mn-Sn合金 近平衡凝固 微观结构 

分 类 号：TG139.6[一般工业技术—材料科学与工程]