Hysteresis of the martensitic phase transition in magnetocaloric-effect Ni-Mn-Sn alloys
Hysteresis of the martensitic phase transition in magnetocaloric-effect Ni-Mn-Sn alloys
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DOI：
10.1103/physrevb.79.144407
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发表时间：
2009-04-01
影响因子：
3.7
通讯作者：
Ohuchi, F. S.
中科院分区：
文献类型：
--
作者：
Shamberger, P. J.;Ohuchi, F. S.
研究了Ni(50.4)Mn(34.0)Sn(15.6)中温度和磁场诱导的马氏体相变的滞后现象。具体地说，我们使用磁化作为存在的相的比例的代理，表征了沿着各种温度和磁场路径存在的马氏体相和立方Heusler相的比例。我们给出了这些结果，并讨论了(1)热致和磁场诱导磁滞的热力学和(2)这种磁滞对合金磁热效应的影响。我们证明了温度和磁场都是相变的等效驱动力，并导致了通过磁吉布斯自由能联系起来的等效磁滞行为。磁滞降低了合金的有效磁热效应，因为在施加和去除高达9T的磁场的情况下，只允许有限部分的合金在马氏体和奥氏体相之间循环转变，并通过不可逆的能量损失来耗散功。虽然大的热力学可逆磁熵变化的重要性被普遍接受，但我们的结果表明，在评估材料的有效磁热效应时，磁滞行为同样重要。
We have investigated the hysteresis of the temperature- and magnetic field-induced martensitic phase transition in Ni(50.4)Mn(34.0)Sn(15.6). Specifically, we have characterized the fraction of martensite and cubic Heusler phase present along a variety of temperature and magnetic field paths using magnetization as a proxy for the fraction of phases present. We present these results and discuss (1) the thermodynamics of the thermal- and magnetic field-induced hysteresis and (2) the impact of this hysteresis on the magnetocaloric effect of the alloy. We demonstrate that both temperature and magnetic field are equivalent driving forces for the phase transition and result in equivalent hysteresis behavior linked through the magnetic Gibbs free energy. The hysteresis reduces the useful magnetocaloric effect of the alloy by allowing only a limited fraction of the alloy to transform cyclicly between the martensite and the austenite phase under application and removal of magnetic fields up to 9 T, and by dissipating work through irreversible energy loss. While the importance of a large thermodynamically reversible magnetic entropy change is generally accepted, our results suggest that the hysteresis behavior is equally critical in evaluating the effective magnetocaloric effect of a material.