Understanding Mechanisms in Magneto-Structural Transformations

了解磁结构转变的机制

• 批准号: 1636105
• 负责人: Patrick Shamberger
• 金额: $ 38.18万
• 依托单位: Texas A&M Engineering Experiment Station
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-01 至 2020-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1636105&HistoricalAwards=false
• 关键词: Understanding; Mechanisms; Magneto; Structural; Transformations

Refrigeration and building cooling account for 17 percent of total electricity consumption in the US. High efficiency magnetic refrigerants, which heat up or cool down in response to external magnetic fields, have the potential to replace traditional vapor-compression refrigerators and heat pumps, dramatically reducing electricity consumption and radically altering the domestic energy landscape. However, these materials are currently limited by energy loss that occurs every time the magnetic field is changed, associated with abrupt changes in the internal structure of the material. This award supports research into the microscopic mechanism causing this energy loss, in order to understand its fundamental origin. This research will result in a better understanding of how to design high-efficiency near-room temperature magnetic refrigerants. Such knowledge could also improve the design of other functional materials such as shape memory alloys.Hysteresis plays a critical role in limiting the efficiency of functional solid-solid phase transitions. While substantial theory has been developed to design low-hysteresis first-order phase transitions in thermoelastic martensites, it remains unclear why certain materials systems exhibit significantly larger hysteresis than other systems. This research seeks to investigate the phase transformation mechanisms in Fe2P alloys, which can exhibit hysteresis 1 K, with the objective of identifying the origins of hysteresis in that system. The research plan consists of three goals: 1) Identify microscopic transformation mechanisms in first-order magneto-structural phase transitions in Fe2P alloys, and detect processes that could significantly contribute to hysteresis; 2) Elucidate the origin of hysteresis and its relationship to a shift from first-order to second-order transition behavior; and 3) Analyze magnetic refrigerant cycle-based performance for low-hysteresis alloys. This research aims to achieve a rational approach to design new low-hysteresis Fe2P alloys, and may additionally provide greater insight into hysteresis engineering in other solid-solid phase transitions.

制冷和建筑冷却占美国总电力消耗的17%。高效磁制冷剂可根据外部磁场加热或冷却，有可能取代传统的蒸汽压缩制冷机和热泵，大幅降低电力消耗，并从根本上改变国内能源格局。 然而，这些材料目前受到每次磁场变化时发生的能量损失的限制，与材料内部结构的突然变化有关。 该奖项支持研究导致这种能量损失的微观机制，以了解其根本原因。 该研究将有助于更好地理解如何设计高效的近室温磁制冷剂。 这些知识也可以改善其他功能材料的设计，如形状记忆合金。滞后在限制功能性固-固相变的效率方面起着关键作用。 虽然大量的理论已经发展到设计低滞后的热弹性马氏体的一级相变，它仍然不清楚为什么某些材料系统表现出显着更大的滞后比其他系统。 本研究旨在探讨Fe 2 P合金的相变机制，它可以表现出滞后1 K，在该系统中的滞后的起源确定的目标。 该研究计划包括三个目标：1）确定Fe 2 P合金中一阶磁结构相变的微观转变机制，并检测可能显著导致磁滞的过程; 2）阐明磁滞的起源及其与从一阶到二阶转变行为的关系; 3）分析低磁滞合金的磁制冷剂循环性能。 本研究的目的是实现一个合理的方法来设计新的低滞后Fe 2 P合金，并可能另外提供更多的洞察滞后工程在其他固-固相变。

项目成果

Size effects in the martensitic transformation hysteresis in Ni–Mn–Sn Heusler alloy films

• DOI: 10.1016/j.actamat.2019.09.001
• 发表时间: 2019-11
• 期刊: Acta Materialia
• 影响因子: 9.4
• 作者: Yijia Zhang;J. Billman;P. Shamberger

Effect of carbide formation on phase equilibria and compositional modulation of transformation properties in (Mn,Fe)2(P,Si) alloys

• DOI: 10.1016/j.jallcom.2020.154532
• 发表时间: 2020-02
• 期刊: Journal of Alloys and Compounds
• 影响因子: 6.2
• 作者: T. Brown;D. Galvan;J. V. Buskirk;A. Mott;P. Shamberger

Effects of hysteresis and Brayton cycle constraints on magnetocaloric refrigerant performance

• DOI: 10.1063/1.5022467
• 发表时间: 2018-05-14
• 期刊: JOURNAL OF APPLIED PHYSICS
• 影响因子: 3.2
• 作者: Brown, T. D.;Buffington, T.;Shamberger, P. J.
• 通讯作者: Shamberger, P. J.