Anomalous physical properties of Heusler-type Co2Cr(Ga,Si) alloys and thermodynamic study on reentrant martensitic transformation
Anomalous physical properties of Heusler-type Co2Cr(Ga,Si) alloys and thermodynamic study on reentrant martensitic transformation
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DOI：
10.1103/physrevb.91.104434
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发表时间：
2015-03-31
影响因子：
3.7
通讯作者：
Kainuma, Ryosuke
中科院分区：
文献类型：
--
作者：
Xu, Xiao;Nagasako, Makoto;Kainuma, Ryosuke
对表现出重入马氏体相变 (RMT) 行为的 Co2Cr(Ga,Si) 基形状记忆合金的电子、磁性和热力学性能进行了实验研究。对于电阻率（ER），发现母相具有逆（类似半导体）温度依赖性，并且在低于其居里温度时出现异常行为。确定了伪二元相图，该图给出了清楚地显示重入行为的“马氏体环”。使用差示扫描量热法和比热测量来推导马氏体和母相之间的熵变 Delta S。对所得 Delta S 的温度依赖性进行了热力学分析，以确认 RMT 和正常马氏体转变的出现。还对低温下马氏体和母相的比热进行了详细研究。
Electronic, magnetic, and thermodynamic properties of Co2Cr(Ga,Si)-based shape-memory alloys, which exhibit reentrant martensitic transformation (RMT) behavior, were studied experimentally. For electric resistivity (ER), an inverse (semiconductor-like) temperature dependence in the parent phase was found, along with anomalous behavior below its Curie temperature. A pseudobinary phase diagram was determined, which gives a "martensite loop" clearly showing the reentrant behavior. Differential scanning calorimetry and specific-heat measurements were used to derive the entropy change Delta S between martensite and parent phases. The temperature dependence of the derived Delta S was analyzed thermodynamically to confirm the appearances of both the RMT and normal martensitic transformation. Detailed studies on the specific heat in martensite and parent phases at low temperatures were also conducted.