We present here the improved crystallographic/geometric compatibility and magnetocaloric reversibility by measurement of magnetic entropy change using different protocols in 10% Pt substituted Ni2Mn1.4In0.6 magnetic shape memory alloy. The substitution of Pt reduces the thermal hysteresis about 50% to the Ni2Mn1.4In0.6. The origin of the reduced thermal hysteresis is investigated by the crystallographic compatibility of the austenite and martensite phases. The calculated middle eigenvalue of the transformation matrix turned out to be 0.9982, which is very close to 1 (deviation is only 0.18%) suggests for the crystallographic compatibility between the austenite and martensite phases in Ni1.9Pt0.1Mn1.4In0.6. A very small thermal hysteresis and crystallographic compatibility between two phases in this alloy system indicate a stress-free transition layer (i.e. perfect habit plane) between the austenite and martensite phase, which is expected to give reversible martensite phase transition and therefore reversible magnetocaloric effect (MCE) as well. The calculated value of the isothermal entropy change (ΔSiso) using the magnetization curve under three different measurement protocols (i.e. isothermal, loop, and isofield measurement protocol) is found to be nearly same indicating a reversible MCE in the present alloy system. Our work provides a path to design new magnetic shape memory Heusler alloys for magnetic refrigeration and also suggest that any of the above measurement protocol can be used for the calculation of ΔSiso for materials satisfying geometrical compatibility condition.
Direct measurements of the magnetocaloric effect in ribbon samples of Heusler alloys Ni - Mn - M (M = In, Sn)
直接测量的磁热效应在快速淬火薄带的Mn 50 Ni 40 In 10和Ni 50 Mn 37 Sn 13 Heusler合金,在磁制冷技术的潜在应用,样品进行。测量是通过一种精确的方法进行的,该方法是基于测量样品在受到调制磁场的同时温度的振荡幅度。在所研究的成分中,发现了与磁性(顺磁体-铁磁体-反铁磁体)和结构(奥氏体-马氏体)相变相关的正磁热效应和逆磁热效应,在铁磁相变附近还观察到了小值的逆磁热效应。
Giant magnetocaloric effect driven by first-order magneto-structural transition in cosubstituted Ni-Mn-Sb Heusler compounds: predictions from \textit{Ab initio} and Monte Carlo calculations
利用密度泛函理论和热力学模型[Physical Review B 86,134418(2012)],在本文中,我们提供了一种方法来系统地筛选给定Heusler家族的化合物,以预测可以产生由一级磁结构转变驱动的巨磁热效应的化合物。我们将这种方法应用到两个Heusler系列Ni $_{2-x}$ Fe $_{x}$ Mn $_{1+z-y}$ Cu $_{y}$ Sb $_{1-z}$和Ni $_{2-x}$ Co $_{x}$ Mn $_{1+z-y}$ Cu $_{y}$ Sb $_{1-z}$,通过在Ni和Mn位点的共取代获得。我们预测了四个新的化合物,有潜力实现目标性能。我们的热力学参数的计算,相关的磁热应用程序,表明在预测的cosubstituted化合物的参数的改善可以是大的四倍相比,非化学计量的Ni-Mn-Sb和衍生的化合物在Ni网站,磁热效应已被实验观察到的单取代。这项工作建立了一个协议,以选择新的化合物,可以表现出大的磁热效应,并证明cosubstitution作为一种途径,更灵活的调谐器,以实现的结果,比现有的。
Improved magnetostructural and magnetocaloric reversibility in magnetic Ni-Mn-In shape-memory Heusler alloy by optimizing the geometric compatibility condition
本文报道了磁性形状记忆合金Ni $_{1.8}$ Mn $_{1.8}$ In $_{0.4}$的磁致伸缩可逆性和逆磁热效应的改善。我们表明,磁致伸缩和MCE的关键取决于奥氏体和马氏体相的几何相容性。从X射线衍射数据计算的变换矩阵中获得了关于两相相容性的详细信息。晶格参数的唯一性导致磁致伸缩和MCE的可逆性改善。在马氏体相变的热滞区,脉冲磁场作用下的最大相对长度变化为0.3%,绝热温度变化为$ΔT_{ad}\approx -10$ K。我们的研究结果表明,几何相容性的方法将允许一个设计材料的可逆磁致伸缩和可逆逆MCE在一阶磁结构相变的形状记忆Heusler合金。
Influence of Gd-rich precipitates on the martensitic transformation, magnetocaloric effect and mechanical properties of Ni-Mn-In Heusler alloys -- A comparative study
Technical University of Darmstadt(达姆施塔特工业大学);Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beihang University(北京航空航天大学材料科学与工程学院航空航天材料与性能教育部重点实验室)
Tailoring magnetocaloric effect in all-d-metal Ni-Co-Mn-Ti Heusler alloys: a combined experimental and theoretical study
新型Ni-Co-Mn-Ti全金属Heusler合金由于其大的多元效应和增强的机械性能而令人兴奋。一系列这些化合物的优化热处理导致块体合金中非常急剧的相变,对于2 T的磁场变化,等温熵变高达38 J kg $^{-1}$ K $^{-1}$。通过光学显微镜对铸态和退火态试样的显微组织和相变进行了详细的研究,分析了铸态和退火态试样的差异。我们确定不同的晶粒结构,以及化学计量(在)均匀性的原因不同尖锐的马氏体相变后,理想和非理想退火。我们开发的合金设计规则调整的磁结构相变和具体评估的转变温度对外部施加的磁场($\frac{dT_t}{μ_0dH}$)通过分析不同的化学计量的敏感性。然后,我们建立了一个相图,包括马氏体转变温度和奥氏体居里温度取决于不同的Co和Ti含量的e/a比。居里温度的演变与化学计量比的变化进行比较,其他Heusler系统。密度泛函理论计算揭示了T $_C$与奥氏体的化学计量以及有序状态的相关性。这种实验和理论相结合的方法允许有效地开发新系统,以实现有前途的磁热性能。直接绝热温度变化测量表明,在1.93 T的磁场变化下,Ni $_{35}$ Co $_{15}$ Mn $_{37}$ Ti $_{13}$的最大变化为-4 K。
Development of a self-consistent thermodynamically optimized database along with phase transition experiments in Ni-Mn-Ga system for magnetocaloric applications
Microstructure engineering of metamagnetic Ni-Mn-based Heusler compounds by Fe-doping: A roadmap towards excellent cyclic stability combined with large elastocaloric and magnetocaloric effects
Magnetovolume Effects in Heusler Compounds via First-Principles Calculations
Heusler合金由于具有高的磁热效应和磁体积效应,在包括磁制冷在内的多种应用中具有广阔的前景。优化这种潜力的一种方法是通过增加磁体积效应。采用密度泛函理论和Korringa-Kohn-Rostoker方法,计算了几种L2 1型Co2 YZ Heusler合金的有效交换相互作用能和相应的平均场居里温度随体积(静水压力)的变化.不同的定性趋势和迹象的居里温度和力矩的压力导数中发现这些化合物,讨论和以前的计算和实验进行比较。
Effect of chemical and hydrostatic pressure on the coupled magnetostructural transition of Ni-Mn-In Heusler alloys
Ni-Mn-In磁性形状记忆Heusler合金在其一级马氏体相变时普遍存在较大的热滞,这阻碍了其在磁制冷领域的应用。通过优化Ni $_2$ Cu $_x$ Mn $_{1.4-x}$ In $_{0.6}$中的Cu含量,得到了Ni $_{2}$ Cu $_{0.2}$ Mn $_{1.2}$ In $_{0.6}$中马氏体相变的热滞仅为6 K。我们可以解释这个非常小的滞后马氏体和奥氏体相的界面处的一个几乎完美的惯习平面。流体静压的应用不会进一步降低滞后,但将马氏体转变移到接近室温。等温熵变不依赖于加热或冷却协议,并且与压力无关。在脉冲磁场下对Ni $_{2}$ Cu $_{0.2}$ Mn $_{1.2}$ In $_{0.6}$的磁热效应进行了研究,发现其最大绝热温度变化为-13 K.
Additive manufacturing of Ni-Mn-Sn shape memory Heusler alloy -- Microstructure and magnetic properties from powder to printed parts
Technical University of Darmstadt(达姆施塔特工业大学);University of Kassel(卡塞尔大学);Fraunhofer Institution for Material Cycles and Resource Strategies IWKS(弗劳恩霍夫材料循环与资源策略研究所 IWKS);TU Bergakademie Freiberg(弗莱贝格矿业技术大学)
Fostering Innovation: Streamlining Magnetocaloric Materials Research by Digitalization
Federal Institute for Materials Research and Testing(联邦材料研究与测试研究所);Faculty of Technology and CITEC, Bielefeld University(比勒费尔德大学技术与CITEC学院);Faculty of Physics, Bielefeld University(比勒费尔德大学物理学院);Helmholtz-Zentrum Berlin for Materials and Energy(柏林亥姆霍兹材料与能源中心);Bielefeld Institute for Applied Materials Research, Bielefeld University of Applied Sciences and Arts(比勒费尔德应用材料研究所,比勒费尔德应用技术大学)