Microstructure and phase transformations in a Ni50Mn29Ga16Gd5 alloy with a high transformation temperature
Microstructure and phase transformations in a Ni50Mn29Ga16Gd5 alloy with a high transformation temperature
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DOI：
10.1007/s10853-007-1893-2
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发表时间：
2007-07
影响因子：
4.5
通讯作者：
W. Cai;Li Gao;Z. Gao
中科院分区：
文献类型：
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作者：
W. Cai;Li Gao;Z. Gao
用5at%Gd替代三元Ni50Mn29Ga21铁磁形状记忆合金中的Ga，获得了高相变温度的Heusler Ni50Mn29Ga16Gd5合金。采用扫描电镜、透射电镜、X射线衍射和差示扫描量热法研究了Ni50Mn29Ga16Gd5合金的显微组织和相变。结果表明，Ni50Mn29Ga16Gd5合金的显微组织由基体和六方Gd（Ni，Mn）4Ga相组成，为两相共晶组织。该四元合金发生一步热弹性马氏体相变。Ni50Mn29Ga16Gd5合金的马氏体相变起始温度高达524K，比Ni50Mn29Ga21合金高出约200K。在室温下，Ni50Mn29Ga16Gd5合金中观察到了孪晶亚结构的非调制马氏体。
A Heusler Ni50Mn29Ga16Gd5alloy with a high transformation temperature has been obtained by substituting 5 at% Gd for Ga in a ternary Ni50Mn29Ga21ferromagnetic shape memory alloy. The microstructure and phase transformations in the Ni50Mn29Ga16Gd5alloy have been investigated by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and differential scanning calorimetry. It is shown that the microstructure of the Ni50Mn29Ga16Gd5alloy consists of matrix and hexagonal Gd (Ni,Mn)4Ga phase, which indicates a eutectic structure composed of these two phases. One-step thermoelastic martensitic transformation occurs in this quaternary alloy. Ni50Mn29Ga16Gd5alloy exhibits a martensite transformation start temperature up to 524 K, approximately 200 K higher than that of Ni50Mn29Ga21alloy. At room temperature, non-modulated martensite with twin substructure is observed in Ni50Mn29Ga16Gd5alloy.