Tuning macro-twinned domain sizes and the b-variants content of the adaptive 14-modulated martensite in epitaxial Ni–Mn–Ga films by co-sputtering
Tuning macro-twinned domain sizes and the b-variants content of the adaptive 14-modulated martensite in epitaxial Ni–Mn–Ga films by co-sputtering
复制标题
DOI：
10.1016/j.actamat.2010.09.006
复制
发表时间：
2010-11
期刊：
影响因子：
9.4
通讯作者：
J. Tillier;D. Bourgault;P. Odier;L. Ortega;S. Pairis;O. Fruchart;N. Caillault;L. Carbone
中科院分区：
文献类型：
--
作者：
J. Tillier;D. Bourgault;P. Odier;L. Ortega;S. Pairis;O. Fruchart;N. Caillault;L. Carbone
为了在我们的外延Ni-Mn-Ga薄膜中获得调制马氏体，我们使用共溅射工艺调整了成分。在这里，我们介绍了成分如何影响室温下14调制马氏体的变化分布。这种调制马氏体的性质在磁性形状记忆合金中仍有很大的争议。最近的研究表明，Ni-Mn-Ga中的调制马氏体是自适应相。这里提出的结果首次证实了这一理论，针对三种不同的成分。此外，我们利用自适应调制理论证明，14调制马氏体的b变异体在薄膜的自由表面附近形成，以释放在刚性基体上马氏体转变过程中由宏观孪晶畴分支引起的应力。在室温下，随着宏观孪晶畴尺寸的增大，这些b变异体的含量明显减少。
In order to obtain modulated martensite in our epitaxial Ni–Mn–Ga films, we tuned the composition by using a co-sputtering process. Here we present how the composition affects the variant distribution of the 14-modulated martensite at room temperature. The nature of such modulated martensites is still strongly debated for magnetic shape memory alloys. It has been very recently demonstrated that the modulated martensites in Ni–Mn–Ga are adaptive phases. The results presented here corroborate this theory for the first time, for three different compositions. Moreover, we demonstrate with the help of the adaptive modulations theory that b-variants of the 14-modulated martensite form close to the free surface of the film to release the stress induced by branching of macro-twinned domains during the martensitic transformation on a rigid substrate. At room temperature, the content of such b-variants is found to strongly decrease when the macro-twinned domain sizes increase.