电弧炉熔炼的Gd2Co2Al合金在铸态条件下即为W2Co2B型单相正交结构。变温磁化曲线表明,当外加磁场为0.01和0.1T时,可以在40、77和215K附近观察到磁相变;而外加磁场增加到1T以上时,40和215K温度处的磁相变消失。在排除第二相相变的前提下,推测215和77K处的相变对应Gd2Co2Al合金中Co和Gd次晶格的磁有序相变,而40K处的相变可能是由于自旋重取向产生。在0～5T磁场变化下,Gd2Co2Al合金在77K附近的最大磁熵变（-ΔSMmax）为10.7J/kgK,相对制冷量的值为5.4×102J/kg,表明该合金适合作为工作在液氮温区附近的磁致冷工质。
Gd2Co2Al alloy synthesized by arc melting was W2Co2B-type single-phase structure in the as-cast state.It can be seen from the temperature dependence magnetization that three magnetic phase transitions occurred at 40,77 and 215K,respectively,when the applied field was under 0.1T.However,only one transition occurring at 77K can be observed when the applied was above 1T.It was speculated that the transitions at 215 and 77K corresponded to the ordering temperatures of Co,and Gd sub-lattice,respectively,and the transition at 40K was a spin-reorietation.The maximal magnetic entropy change（-ΔSMmax） under 0-5T is about 10.7J/kgK occurring at 77K and the relative cooling powder（RCP） is about 5.4×102J/kg,which makes Gd2Co2Al alloy a promising candidate magnetic refrigerant near liquid-nitrogen temperatures.
参考文献
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