Fe substitution induced intermartensitic transition and its internal stress dependent transforming behavior in Ni-Mn-Ga based alloy

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• 作者：Chonghui Huang ; Yu Wang ; Haijun Wu ; Xiaoqi Liao ; Sen Yang ; Songrui Wei ; Jieqiong Wang ; Xiaoping Song
• 关键词：Intermartensitic transition ; Martensitic transition ; Internal stress ; Ni&ndash ; Mn&ndash ; Ga ; Ferromagnetic shape memory alloy
• 刊名：Journal of Alloys and Compounds
• 出版年：2013
• 出版时间：25 December, 2013
• 年：2013
• 卷：581
• 期：Complete
• 页码：812-815
• 全文大小：1077 K

文摘

The transforming behavior of Fe doped Ni₅₅Mn₂₀Ga₂₅ ferromagnetic shape memory alloys is investigated in this study. The Ni₅₅Mn₂₀Ga₂₅ alloy only undergoes P (parent phase) ¡ú non-modulated T (non-modulated tetragonal martensite) martensitic transition. It does not exhibit intermartensitic transition, since the non-modulated T structure is the most stable martensitic state in Ni-Mn-Ga system. However, 2 % (at.) Fe substitution for Ni of the Ni₅₅Mn₂₀Ga₂₅ alloy induces an intermartensitic transition and the transition sequence of Ni₅₃Fe₂Mn₂₀Ga₂₅ alloy changes into P (parent phase) ¡ú 7 M (seven-layer modulated martensite) ¡ú non-modulated T. It was also found that the intermartensitic transition of Ni₅₃Fe₂Mn₂₀Ga₂₅ alloy can be suppressed by the internal stress produced by water quenching and sample crushing. This is considered to stem from the inhomogeneous and non-directional internal stress states generated during water quenching and sample crushing process.