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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
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- DOI:
- 作者:
- 翟 强 1 ， 2 ，卜 凡 1 ， 2 ，马昌尧 1 ，刘子瑜 1 ，贺一轩 1 ， 2 ，王 军
ZHAI Qiang 1,2 , BU Fan 1,2 , MA Changyao 1 , LIU Ziyu 1 , HE Yixuan 1,2 , WANG Jun 2 , LI Jinshan 2
- 作者单位:
- 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
1. Center of Advanced Lubrication and Seal Materials, Northwestern Polytechnical University, Xi'an 710072, China; 2. State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi'an 710072, China
- 关键词:
- 强磁场； Ni-Co-Mn-Sn 合金；近平衡凝固；微观结构
strong magnetic field; Ni-Co-Mn-Sn alloy; near-equilibrium solidification; microstructure
- 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 Ni 42 Co 8 Mn 39 Sn 11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 D0 3 型粗大枝晶及 L2 1 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 ， D0 3 相富 Sn 贫 Co ， L2 1 相的成分接近名义配比；D0 3 结构由 L2 1 结构产生的成分偏析区域形成，析出 γ 相并非低温下 L2 1 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 D0 3 相含量减少， L2 1 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 Ni 42 Co 8 Mn 39 Sn 11 MSMA under different magnetic field intensities were studied. The results show that in the absence of magnetic field, the microstructure is mainly composed of D0 3 coarse dendrite trunks and L2 1 interdendrite, embedded with the vermicular γ phase that is Co-rich and Sn-depleted, and the chemical composition of the D0 3 phase shows the opposite tendency. The D0 3 structure is formed due to the chemical segregation of the Heusler L2 1 phase, and the γ phase is hardly obtained from the decomposition of the L2 1 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 D0 3 phase decreases efficiently, and the L2 1 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.