arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2004.01854cond-mat.mtrl-sciphysics.app-ph
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Pt取代Ni2Mn1.4In 0.6磁性形状记忆合金的晶体相容性和磁热可逆性的改善

Improved crystallographic compatibility and magnetocaloric reversibility in Pt substituted Ni2Mn1.4In0.6 magnetic shape memory Heusler alloy

K. K. Dubey, P. Devi, Anupam K. Singh, Sanjay Singh

摘要:

我们在这里提出了改进的结晶/几何相容性和磁热可逆性的测量磁熵变使用不同的协议在10%Pt取代的Ni 2 Mn 1.4In 0.6磁性记忆合金。Pt的替代使Ni2Mn1.4In0.6合金的热滞效应降低了约50%。降低的热滞后的起源是由奥氏体和马氏体相的晶体学相容性研究的。计算得到的变换矩阵的中间特征值为0.9982,与1非常接近(偏差仅为0.18%),表明Ni1.9Pt0.1Mn1.4In0.6中奥氏体和马氏体相之间存在晶体学相容性。该合金体系中两相之间的非常小的热滞后和晶体学相容性表明奥氏体和马氏体相之间的无应力过渡层(即,完美惯习面),预期其产生可逆的马氏体相变,因此也产生可逆的磁热效应(MCE)。在三种不同的测量方案(即等温、环和等场测量方案)下使用磁化曲线计算的等温熵变(ΔSiso)的值被发现几乎相同,表明本合金系统中的可逆MCE。我们的工作为设计新型的磁性形状记忆Heusler合金提供了一条途径,同时也表明上述任何一种测量方案都可以用于满足几何相容条件的材料ΔSiso的计算。

英文摘要:

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.

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