中国物理B ›› 2024, Vol. 33 ›› Issue (4): 48103-048103.doi: 10.1088/1674-1056/ad188d

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Pre-existing orthorhombic embryos-induced hexagonal—orthorhombic martensitic transformation in MnNiSi1-x(CoNiGe)x alloy

Ting-Ting Zhang(张婷婷), Yuan-Yuan Gong(龚元元), Zi-Qian Lu(鲁子骞), and Feng Xu(徐锋)   

  1. MIIT Key Laboratory of Advanced Metallic and Intermetallic Materials Technology, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China
  • 收稿日期:2023-09-18 修回日期:2023-12-17 接受日期:2023-12-25 出版日期:2024-03-19 发布日期:2024-03-27
  • 通讯作者: Feng Xu E-mail:xufeng@njust.edu.cn
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant No. 11974184).

Pre-existing orthorhombic embryos-induced hexagonal—orthorhombic martensitic transformation in MnNiSi1-x(CoNiGe)x alloy

Ting-Ting Zhang(张婷婷), Yuan-Yuan Gong(龚元元), Zi-Qian Lu(鲁子骞), and Feng Xu(徐锋)   

  1. MIIT Key Laboratory of Advanced Metallic and Intermetallic Materials Technology, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China
  • Received:2023-09-18 Revised:2023-12-17 Accepted:2023-12-25 Online:2024-03-19 Published:2024-03-27
  • Contact: Feng Xu E-mail:xufeng@njust.edu.cn
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant No. 11974184).

摘要: The thermal—elastic martensitic transformation from high-temperature Ni$_{2}$In-type hexagonal structure to low-temperature TiNiSi-type orthorhombic structure has been widely studied in Mn$MX$ ($M={\rm Ni}$ or Co, and $X={\rm Ge}$ or Si) alloys. However, the answer to how the orthorhombic martensite nucleates and grows within the hexagonal parent is still unclear. In this work, the hexagonal—orthorhombic martensitic transformation in a Co and Ge co-substituted MnNiSi is investigated. One can find some orthorhombic laths embedded in the hexagonal parent at a temperature above the martensitic transformation start temperature ($M_{\rm s}$). With the the sample cooing to $M_{\rm s}$, the laths turn broader, indicating that the martensitic transformation starts from these pre-existing orthorhombic laths. Microstructure observation suggests that these pre-existing orthorhombic laths do not originate from the hexagonal—orthorhombic martensitic transformation because of the difference between atomic occupations of doping elements in the hexagonal parent and those in the pre-existing orthorhombic laths. The phenomenological crystallographic theory and experimental investigations prove that the pre-existing orthorhombic lath and generated orthorhombic martensite have the same crystallography relationship to the hexagonal parent. Therefore, the orthorhombic martensite can take these pre-existing laths as embryos and grow up. This work implies that the martensitic transformation in MnNiSi$_{1-x}$(CoNiGe)$_{x}$ alloy is initiated by orthorhombic embryos.

关键词: martensitic transformation, MnMX alloy, orthorhombic embryo, crystallography relationship

Abstract: The thermal—elastic martensitic transformation from high-temperature Ni$_{2}$In-type hexagonal structure to low-temperature TiNiSi-type orthorhombic structure has been widely studied in Mn$MX$ ($M={\rm Ni}$ or Co, and $X={\rm Ge}$ or Si) alloys. However, the answer to how the orthorhombic martensite nucleates and grows within the hexagonal parent is still unclear. In this work, the hexagonal—orthorhombic martensitic transformation in a Co and Ge co-substituted MnNiSi is investigated. One can find some orthorhombic laths embedded in the hexagonal parent at a temperature above the martensitic transformation start temperature ($M_{\rm s}$). With the the sample cooing to $M_{\rm s}$, the laths turn broader, indicating that the martensitic transformation starts from these pre-existing orthorhombic laths. Microstructure observation suggests that these pre-existing orthorhombic laths do not originate from the hexagonal—orthorhombic martensitic transformation because of the difference between atomic occupations of doping elements in the hexagonal parent and those in the pre-existing orthorhombic laths. The phenomenological crystallographic theory and experimental investigations prove that the pre-existing orthorhombic lath and generated orthorhombic martensite have the same crystallography relationship to the hexagonal parent. Therefore, the orthorhombic martensite can take these pre-existing laths as embryos and grow up. This work implies that the martensitic transformation in MnNiSi$_{1-x}$(CoNiGe)$_{x}$ alloy is initiated by orthorhombic embryos.

Key words: martensitic transformation, MnMX alloy, orthorhombic embryo, crystallography relationship

中图分类号:  (Martensitic transformations)

  • 81.30.Kf
81.05.Bx (Metals, semimetals, and alloys) 68.55.A- (Nucleation and growth) 61.50.Ks (Crystallographic aspects of phase transformations; pressure effects)