Abstract This study is based on X-ray diffraction (XRD) and DSC analysis, Scanning Electron Microscopy (SEM) and Optical Microscope observations and Vickers Micro Hardness Test results with structural effect and phase transformations on NiMnGa shape memory alloys with different composition. The addition of different elements to the shape-memory NiMnGa alloys and the heat treatment of the alloys are extremely useful for improving the shape memory, magnetic, mechanical, chemical and other physical properties. The NiMnGaMo alloys were successfully obtained using a vacuum induction melting furnace and then homogenized by heat treatment at 950 °C for 2, 24 and 96 h, respectively. After homogenization, all samples were cooled in ice water. Crystallographic results calculated from XRD data were evaluated by comparison with the data obtained by DSC analysis, Scanning Electron Microscope (SEM), Optical Microscope and Vickers Micro Hardness Test Device. The results show that the alloy with a higher Mo amount has a smaller crystallite size and the L21 lattice volume increases with heat treatment time. The change on microhardness values were discussed with the change on the obtained lattice constants.

中文翻译：

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均质化时间对NiMnGaMo合金晶体结构和硬度的影响

摘要 本研究基于 X 射线衍射 (XRD) 和 DSC 分析、扫描电子显微镜 (SEM) 和光学显微镜观察以及维氏显微硬度测试结果以及不同成分的 NiMnGa 形状记忆合金的结构效应和相变。在形状记忆 NiMnGa 合金中添加不同元素和合金的热处理对于改善形状记忆、磁、机械、化学和其他物理性能非常有用。使用真空感应熔炼炉成功获得 NiMnGaMo 合金，然后通过在 950°C 下分别热处理 2、24 和 96 小时进行均质化。均化后，所有样品在冰水中冷却。通过与由 DSC 分析、扫描电子显微镜 (SEM)、光学显微镜和维氏显微硬度测试设备获得的数据进行比较，评估从 XRD 数据计算出的晶体学结果。结果表明，Mo含量较高的合金晶粒尺寸较小，L21晶格体积随着热处理时间的增加而增加。讨论了显微硬度值的变化与获得的晶格常数的变化。