Gd99.75Fe0.25合金的大磁热效应及应用特性研究

采用X射线衍射、物理性能测试系统、显微硬度计及电化学工作站研究了经氩弧熔炼、1123 K均匀化热处理168 h的 Gd99.75Fe0.25合金的磁热效应及应用特性。结果表明：Gd99.75Fe0.25合金仍保持纯Gd的六方晶体结构；Gd99.75Fe0.25合金的居里温度为294 K，且在居里点附近发生铁磁到顺磁的二级相变，2和5 T外场下的最大磁熵变分别为4.99和9.37 J·kg-1·K-1，均大于纯Gd；Gd99.75Fe0.25合金的显微硬度（HV0.2）590 MPa，与纯Gd相当，但少量Fe的掺杂提高了Gd的耐蚀性。含少量Fe的Gd99.75Fe0.25合金具有大的磁热效应及良好的应用特性，是一种有很大应用潜力的室温磁致冷材料。

Large Magnetocaloric Effect and Application Features of Gd99.75Fe0.25 Alloy

Gd99.75Fe0.25 alloy prepared by arc melting under purified argon atmosphere and homogenization annealing treatment at 1123 K for 168 h was investigated by X-ray diffraction, physical property measurement system, microhardness tester and electrochemical workstation. The results show that the Gd99.75Fe0.25 alloy still retains hexagonal crystal structure of pure Gd. The Curie temperature of Gd99.75Fe0.25 alloy is 294 K, and the alloy exhibits a second-order magnetic transition from ferromagnetism to paramagnetism. The maximum magnetic entropy changes of Gd99.75Fe0.25 alloy under magnetic field changes of 0~2 T and 0~5 T are 4.99 J·kg-1·K-1 and 9.37 J·kg-1·K-1, respectively, which are larger than that of pure Gd. The micro-hardness (HV0.2) of Gd99.75Fe0.25 alloy is 590 MPa, which is equivalent to that of pure Gd. But the corrosion resistance is improved by doping a small amount of Fe. Large magnetocaloric effect and good application features make the Gd99.75Fe0.25 alloy as a potential magnetic refrigerant at room temperature.