NiMn基Heusler合金马氏体相变行为调控研究
结论表明：成分对于合金性能有很大的影响，实验NiMnSn合金中，随Sn元素含量的增加，合金的马氏体相变温度发生降低，这和电子浓度的影响规律相符合，而在Ni45Mn45-xSn10Crx合金中，相变温度随Cr含量的增高变化较复杂，为先降低，后升高。相变温度在室温以下的合金，XRD显示室温时，组成相为奥氏体。23722
Ni45Mn45-xSn10Crx合金的磁学性能表征显示样品的饱和磁化强度随Cr增加降低，并且在发生相变时磁化强度降低的速率随Cr含量增加而变缓。计算发现磁熵随Cr含量增加而减小。所有合金都显示随成分变化奥氏体居里温度几乎不变。
马氏体相变 磁熵变 磁化强度 Heusler合金 成分关键词
毕业设计说明书（毕业论文）外文摘要
Title Martensitic Transformation in NiMn-based Heusler Alloy
Abstract
NiMn-based Heusler alloy has many good performances, such as shape memory, magnetocaloric, which will have a wide range of applications.
In this article, the alloy ingots were prepared by using a vacuum arc furnace, and then the ingots were made into ribbons. We made two series of NiMnSn alloy and one series of NiMnSn(Cr) alloy. The alloy were studied by differential scanning calorimetry (DSC), vibrating sample magnetometry (VSM), and XRD. The change of magnetic properties were characterized. The data obtained by experiment were analyzed.
Conclusion shows that the composition of the alloy has a great impact on the performance of NiMnSn alloys. With the increase of Sn content, the martensitic transformation’s temperature decreased, which are consistent with the influence of the electron concentration. In Ni45Mn45-xSn10Crx alloys, the temperature of phase transition changes versus the content of Cr is more complex. With the increase of of Cr content, the phase-transition temperature at first decreased and then increased. Detected by XRD, we find that the alloys whose martensitic transformation’s temperature is below room temperature exist in the form of austenitic phase.
Characterization of magnetic properties displays the saturation magnetization of the series of Ni45Mn45-xSn10Crx alloy samples decreases with the increase of Cr content, and the change of the magnetization is reduced thought the phase-change and the change rate of the magnetization slows with increase of Cr content. The magnetic entropy decreases with Cr content increases by calculation. For all alloys with different composition, the Curie temperature of austenite are almost unchanged with the change of composition.
Keywords: Martensitic transformation, Magnetization, The change of magnetic entropy, Heusler alloy, Composition
目 次
1 绪论 1
1.1 前言 1
1.2 NiMn基Heusler合金概况 2
1.2.1 典型NiMn基Heusler合金晶体结构 2
1.2.2 NiMn基合金的马氏体相变 3
1.2.3 NiMn基Heusler合金在马氏变体在磁场下的重新排列 4
1.2.4 NiMn基Heusler合金马氏体行为调控及国内外研究现状 5
1.3 选题目的与研究内容 6
2 实验材料的制备和研究方法 7
2.1 实验合金的成分设计与制备 7
2.1.1 实验合金成分设计 7