强磁场下La-Fe-Si基复合磁制冷材料的制备与性能调控

The high magnetic fields as an extreme condition has been well used in the fields of synthesis and processing of novel materials as well adjusting the microstructure during solidification and promoting the related properties of materials. To improve the mechanical and thermal transport properties of La-Fe-Si based magnetic refrigerant materials. The present research will use the hot-pressing method to synthesize the La(Fe,Si)13/M (M=Fe,Cu) that possess first-order magnetic phase transition and the La(Fe,Co,Si)13/M (M=Fe,Cu) that possess second-order magnetic phase transition composite materials under high magnetic fields, respectively. The microstructure, mechanical, thermal, magnetic as well as magnetocaloric properties will be investigated. Try to obtain the secondary phase aligned and distributed evenly in the La-Fe-Si matrix, and enhance the thermal and mechanical properties of the composite materials. The present study may provide some new idea and information to achieve the La-Fe-Si based magnetic refrigeration materials with promising thermal, mechanical as well as magnetocaloric properties. The physical mechanism of high magnetic field treatment on the microstructure evolution and physical properties will be discussed based on the comparison study and related theory.

强磁场作为一种极端实验手段在新材料研发、制备与加工及微观组织和性能调控等方面发挥着重要的作用。为有效提高La-Fe-Si基磁制冷材料的热传导和机械性能，本项目拟利用强磁场下热压成型的方法制备具有一级相变La(Fe,Si)13/M (M=Fe,Cu)和二级相变的La(Fe,Co,Si)13/M (M=Fe,Cu)复合材料，并对其微观组织、机械性能、热传导、磁性和磁热效应等相关物理特性进行对比研究。以期通过磁场调控获得第二相均匀、有序分布的复合材料，为获得兼具优异热传导和机械性能及磁热效应的La-Fe-Si基磁制冷材料提供新的思路和方法。并结合相关理论，阐明磁场对La-Fe-Si基磁制冷材料组织演变和相关物理性能调控的物理机制。

基于磁热效应的磁制冷技术因其具有绿色环保和高效节能等优点有望成为替代现有的气体压缩制冷的新型制冷技术之一。探索或设计出高性能磁制冷材料是当前研究热点之一。本课题利用热压成型的方法制备了系列La(Fe,Si)13基复合磁制冷材料，并对其微观组织、机械性能、热传导以及强磁场下的磁性和磁热效应等物理特性进行了系统研究。获得了系列第二相均匀、有序分布的La(Fe,Si)13基复合磁制冷材料，而且发现该类复合材料具有优异的力学性能且同时保持较大的磁制冷特性。此外，我们合成了系列稀土金属间化合物与稀土过渡金属氧化物材料，并对其晶体结构、磁性和磁热效应以及其在磁制冷领域的应用和相关物理机制进行了系统的分析和研究，并在一些材料中发现优异的低温磁制冷性能。本研究可为高性能磁制冷材料的探索提供一些实验和理论依据。