ABSTRACT In this work, we have investigated the crystalline structure, martensitic transformation (MT) and magnetic properties of Co50V25-xNixGa25 (x = 5, 6, 7, 8, 9, 12.5) together with Co50V17Ni7Ga26 Heusler alloys. It was found that the MT behavior can occur in the Ni-doped Co50V25Ga25 Heusler alloys, and the MT temperature increases with the increase of Ni doping, which can reach about room temperature as the Ni doping increases up to x = 12.5. In the temperature interval of MT, with the decrease of temperature, the metamagnetic behavior appears from the ferromagnetic austenitic phase to the paramagnetic martensitic phase in the Co50V17Ni7Ga26 Heusler alloy. As a result, the magnetocaloric effect was observed, and the calculated magnetic entropy change can achieve about 11.5 J/kg K around 94 K for the magnetic field changes of 7 T.

中文翻译：

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Ni掺杂对Co50V25Ga25∼26 Heusler合金马氏体相变及磁性能的影响

摘要 在这项工作中，我们研究了 Co50V25-xNixGa25 (x = 5, 6, 7, 8, 9, 12.5) 和 Co50V17Ni7Ga26 Heusler 合金的晶体结构、马氏体转变 (MT) 和磁性能。发现掺杂Ni的Co50V25Ga25 Heusler合金会发生MT行为，MT温度随着Ni掺杂量的增加而升高，随着Ni掺杂量增加到x = 12.5，MT温度可以达到约室温。在MT的温度区间，随着温度的降低，Co50V17Ni7Ga26赫斯勒合金中出现从铁磁奥氏体相到顺磁马氏体相的变磁行为。结果，观察到了磁热效应，对于7 T的磁场变化，计算出的磁熵变在94 K附近可以达到约11.5 J/kg K。