Ga对β基Co-Ni-Al铁磁性形状记忆合金马氏体和磁性转变的影响

Influence of Ga on martensitic and magnetic transitions in Co-Ni-Al β-based ferromagnetic shape memory alloys

借助光学金相、示差热分析、振动样品磁强计和x-射线能谱分析等分析方法，研究Ga含量对Co41Ni32-Al27-xGax合金马氏体相变和Curie点的影响。研究结果表明：合金马氏体相变温度与Ga含量成正比，在1573和1623K淬火时，X增加1，马氏体相变温度提高25K，但Ga含量对Curie点影响不大；在1573K淬火时，具有高有序度的马氏体相比B2结构相的Curie点高32K，说明结构有序度对Curie点影响较大；淬火温度升高会显著提高合金的马氏体相变温度和Curie点，当淬火温度从1573K升高到1623K时，马氏体相变温度升高43～69K，Curie点平均升高41K；随着Ga含量的增加，合金的熔点降低，在1623K淬火时Co41Ni32Al18Ga9合金发生部分熔化。

The influences of gallium concentration on martensitic transformation temperature and Curie point of Co41 Ni32 Al27-xGax alloys were investigated by optical micrography, scanning electron microscopy, differential scanning calorimetry and vibrating sample magnetometer and energy dispersive X-ray detector. The results show that the martensitic transformation temperatures of Co41Ni32A127-xGax alloys are linearly increased with Ga content. An increase of 1% in Ga concentration can cause the martensitic transformation temperature to be increased by 25 K for alloys quenched at 1 623 K or at 1 573 K, respectively. The influence on Curie points of Co41Ni32- Al27-xGax alloys is very small. However, the order degree of phase structure has great effects on Curie point. The Curie point of high ordered martensitic phase is higher than that of B2 structure phase by 32 K. Martensitic transformation temperatures increase by 43 - 69 K and Curie points increase by 41 K when the quenched temperatures elevate from 1 573 to 1 623 K. The melting points of Co41Ni32Al27-xGax alloys decrease with the increase of Ga concentration, resulting in the partial melted phenomena of Co41 Ni32 Al18Ga7 alloy quenched at 1 623 K.