一级相变La(Fe, Si)13/M（Cu，Ag）基磁致冷复合材料的热压烧结行为及影响其实用性的关键因素研究

降低一级相变La(Fe,Si)13基块体磁致冷材料的热滞和磁滞，提高其的热传导能力及在热传导流体中的耐腐蚀能力，是关系其实际应用的核心科学问题。本项目拟采用细化La(Fe,Si)13，La(Fe,Si)13Hx合金颗粒来降低热滞及磁滞，开发热压烧结工艺制备高致密、高传热系数及耐腐蚀的实用块体。热压烧结前采用化学镀法在颗粒表面包覆塑性金属M（Cu及Ag），获得La(Fe,Si)13/M，La(Fe,Si)13Hx/M复合结构，帮助抑制合金颗粒热压过程中的过度长大及磁致冷1：13相的分解。分析热压烧结过程中，表面包覆金属对磁致冷合金颗粒长大及磁致冷1：13相分解行为的影响机理；测量烧结样品的磁熵变、热滞、磁滞及导热系数，揭示微结构和物理性能之间的本构关系；研究热压烧结样品在去离子水中的腐蚀行为及其机理。为改善一级相变La(Fe, Si)13系磁致冷复合材料的具体实用性奠定一定的科学基础。

Regarding the practical applications of La(Fe, Si)13-based first order transition magnetocaloric bulk materials, the key scientific issues are of reducing the thermal and magnetic hysteresis, improving the ability of heat transfer and resisting the corrosion of the thermal transfer fluid. In this project, the particles of La(Fe, Si)13, La(Fe, Si)13Hx alloys will be refined to reduce the thermal and magnetic hystereses. The hot-press sintering will be developed to fabricate the bulk materials with the high density, high thermal conductivity and good anti-corrosion ability. For the purpose of inhibiting the severe particle growth and decomposition of 1:13 phases, the surface of the magnetocaloric particles will be coated with the plastic metals M (Cu and Ag) to obtain the composite structures of La(Fe, Si)13/M and La(Fe, Si)13Hx/M (M=Cu, Ag) before hot-press sintering. The effects of the coated metals on the phase stability and particle growth will be investigated during the hot-pressing. The magnetic entropy change, thermal hysteresis, magnetic hysteresis and thermal conductivity will be measured. The intrinsic relationship of the microstructures and physical properties will be analyzed and revealed. The corrosion behavior and its mechanism will be studied in the thermal conductive medium of the distilled water for the hot-pressed bulk samples. The project results will establish some bases in improving the practical capability of the La(Fe, Si)13-based first-order phase transition magnetocaloric composites.