【作者】 黄苍碧；

【导师】 陈云贵；

【作者基本信息】 四川大学 ， 材料学， 2003， 硕士

【摘要】 室温磁制冷技术因具有节能、环保等突出优点，越来越受到人们的关注。磁致冷材料作为其中的关键技术，它的发展具有举足轻重的作用。本文首先就磁致冷的基本原理、磁制冷关键技术、磁致冷材料的发展等问题做了简要的概述。本文研究下列问题并取得进展。第一、采用直接和间接测量法测试了不同纯度Gd在低场下（≦1.5T）的磁热效应；采用比热法计算了磁热效应并同实际测量的磁热效应进行了比较，结果表明Gd的磁热效应随着杂质的增加而减小、居里点降低；第二、对Gd₅Si₂Ge₂和Gd₅Si_1.9Ge₂Sn_0.1合金进行了热处理，实验结果表明高温热处理后，合金铸态的磁热效应得到了改善，其中1200℃/3h液氮冷却热处理后，磁热效应比合金铸态提高3倍多，比钆提高了84％；第三、在Gd₅Si₂Ge₂的研究基础上，采用SEM和XRD等方法，观察Gd₅Si_1.9Ge₂Sn_0.1合金热处理前后微观组织结构的变化，结果表明在热处理缓慢的冷却条件，合金易于出现第二相；高温保温并快速冷却，有利于形成单相，从而改善了磁热效应。更多还原

【Abstract】 Magnetic refrigeration technology at the room temperature has attracted more and more people’s attention due to its advantages involving in energy saving, environmental protection. To be key issue, magnetic refrigeration material has played an important role in the technology.Firstly the article briefly introduces the basic principle, the key technology of magnetic refrigeration and the development of magnetic refrigerants. We have researched some questions and made some progress in this research. The article includes three parts: i) directly and indirectly measure the magnetocaloric effect of the different purity Gd under low magnetic field (<1.5T) , and verify the measured accuracy of the magnetocaloric effect adopting heat capacity. The result indicates that the magnetocaloric effect is reduced with increase of the impurity, Curie temperature decreased, ii) Gd5Si2Ge2 and Gd5Si1.9Ge2Sn0.1 alloy are heat-treated. The result indicates magnetocaloric effect of the alloy ingot have been greatly improved by heat treatment at high temperature, especially they has more three times than the former through heat treated by liquid nitrogen holding 1200℃ for 3h. iii) The microstructure of as-cast and heat-treated Gd5Si1 9Ge2Sn0.1 alloy are watched by SEM and XRD in order to find the cohesive relation between the microstructure and properties. The result indicates the alloy easily forms the second phase by the slower cooling during heat treatment, and makes more easily forming the single phase by holding temperature at high temperature and quicker cooling to improve the magnetocaloric effect.更多还原