Abstract A Ni-Mn-Ga alloy rod with significant axial compositional gradient has been designed by directional solidification at a low growth speed. The axial distributions of Ni and Ga gradually decrease and that of Mn gradually increases, which agrees with Burton-Prim-Slichter relationship. The axial crystal structure changes from austenite to martensite accordingly, and the crystal orientation relationship and the microstructure evolution near the phase interface have been investigated by EBSD and TEM. Moreover, the saturation magnetization along the solidification direction decreases due to the enhancement of anti-ferromagnetic coupling between Mn ions. The present research provides an alternative way not only to investigate martensite/austenite phase interface but also to explore a wide range of compositions and corresponding structures and properties in Ni-Mn-Ga alloys.

中文翻译：

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具有轴向成分变化的定向凝固 Ni-Mn-Ga 棒的结构和磁性能测定

摘要 通过定向凝固低生长速度设计了一种具有显着轴向成分梯度的Ni-Mn-Ga合金棒材。Ni和Ga的轴向分布逐渐减小，Mn的轴向分布逐渐增大，符合Burton-Prim-Slichter关系。轴向晶体结构相应地从奥氏体转变为马氏体，并通过 EBSD 和 TEM 研究了相界面附近的晶体取向关系和微观结构演变。此外，由于Mn离子之间的反铁磁耦合增强，沿凝固方向的饱和磁化强度降低。