摘要
磁制冷技术具有绿色环保、高能效、运行可靠等优点,成为制冷领域研究的焦点.采用真空电弧熔炼技术,制备了 Gd3Al2-xGax(x=0.0、0.1、0.2、0.3)合金,系统地分析了合金的微观结构、磁性和磁热效应.研究结果表明,Gd3Al2合金由Gd3Al2相、GdAl相、Gd2Al相构成.随着Ga含量的增加,杂相GdAl相和Gd2Al相含量逐渐减少,主相Gd3Al2相含量逐渐增加.在Gd3Al2合金中,Ga元素的引入可以起到调控微观结构的作用.M-T曲线表明,Gd3Al2、Gd3Al1.9Ga0.1、Gd3Al1.8Ga0.2 和 Gd3Al1.7Ga0.3 合金的居里温度分别为 274、276、274、276 K,表明Gd3Al2-xGax合金可在室温附近应用.M-H曲线说明,Gd3Al2-xGa,合金在居里温度附近经历顺磁到铁磁转变,为二级磁相变材料.在0～3 T下,Gd3Al2-xGax(x=0.0、0.1、0.2、0.3)合金的最大等温磁熵变分别为3.04、3.23、3.26、3.57 J·kg-1·K-1,RCP 分别为 157.54、184.67、184.39、200.42 J·kg-1.0～2 T 下,Gd3Al2-xGa,(x=0.0、0.1、0.2、0.3)合金的最大绝热温变分别为2.76、3.02、3.37、3.59 K.合适的居里温度、优异的磁热效应表明,Gd3Al2-xGax(x=0.0、0.1、0.2、0.3)合金可作为一种候选室温磁制冷材料.
Abstract
Magnetic refrigeration technology has the advantages of green environment,high energy efficiency and re-liable operation,which has become the focus of research in the field of refrigeration.The Gd3Al2-xGax(x=0.0,0.1,0.2,0.3)alloys were prepared by vacuum arc melting technology,and the microstructure,magnetism and magnetocaloric effect(MCE)were systematically analyzed.The results show that the Gd3Al2 alloy consists of Gd3Al2 phase,GdAl phase,and Gd2Al phase.With the increase of Ga content,the content of heterogeneous phases GdAl phase and Gd2Al phase gradually decreases,and the content of main phase Gd3Al2 phase gradually increases.For Gd3Al2-series alloys,the introduction of Ga element can play a role in modulating the microstructure.The M-T curves show that the Curie temperatures of Gd3Al2、Gd3Al1.9Ga0.1、Gd3Al1.8Ga0.2 and Gd3Al1.7Ga0.3 alloys are 274,276,274,and 276 K,respectively,which indicate that Gd3Al2-xGax alloys can be applied near room temperature.The M-H curves illustrate that every Gd3Al2-xGax alloy undergoes a paramagnetic to ferromagnetic transition near the Curie temperature and belongs to the second order magnetic transition material.The maximum isothermal mag-netic entropy changes of Gd3Al2-xGax(x=0.0,0.1,0.2,0.3)alloys are 3.04,3.23,3.26,3.57 J·kg-1·K-1,with RCPs of 157.54,184.67,184.39,and 200.42 J·kg-1,respectively,at 0-3 T.The maximum adiabatic tem-perature changes of Gd3Al2-xGax(x=0.0,0.1,0.2,0.3)alloys are 2.76,3.02,3.37,3.59 K,respectively.Suit-able Curie temperature and excellent MCE suggest that Gd3Al2-xGax(x=0.0,0.1,0.2,0.3)alloys can be a candi-date for room-temperature magnetic refrigerants.
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