织构型球形合金粉末制备及其复合材料的磁致伸缩和磁致应变研究

Preparation of the textured spherical alloy powders is of great significance to the development of the high performance magnetostrictive composites and the magnetic-field-induced-strain composites. After the summary of present spherical metal powders preparation method the project put forward to prepare fine magnetic alloy spherical powder by no wetting between the metal droplets and solid dispersion material interface. The formation of textured spherical powders of (Tb, Dy)Fe2、MnCoSi or Ni-Mn-Ga alloys will be studied by the way that a magnetic field will be applied during the solidification of the metal droplets. The law of forming spherical particles of (Tb, Dy)Fe2、MnCoSi and Ni-Mn-Ga alloys will be studied when oxide materials are used as dispersion materials and the corresponding best dispersion materials for different magnetic powder will be explored. Effect of heat treatment conditions on the sphericity, crystal structure, composition and related magnetic properties of magnetic powders will be studied. The effect of magnetic field on crystal growth and the texture formation in the process of solidification of magnetic alloys will be studied and the textured spherical particles with same crystal structure and magnetic properties will be fabricated. Study on the magnetostriction and magnetic-field-induced strain of the textured spherical powders / resin based materials composites molded with magnetic field，lay the foundation for the development of the huge magnetostrictive composites and magnetic-field-induced-strain composites.

晶体结构和磁性一致性好的织构型球形磁性合金粉末的制备对发展高性能磁致伸缩和磁致应变复合材料具有重要的意义。本项目在总结目前球形合金粉末制备方法的基础上，提出了通过合金液滴/固体分散材料界面不润湿的方法制备微细磁性合金球形粉末的策略。同时，将通过在磁性合金液滴凝固时外加磁场的方法制备 (Tb,Dy)Fe2、MnCoSi和Ni-Mn-Ga合金织构型球形粉末。研究氧化物做分散材料时(Tb,Dy)Fe2、MnCoSi和Ni-Mn-Ga合金颗粒的球化规律，确定所研究的磁性合金对应的氧化物类型。研究热处理条件对磁性合金颗粒的球形度、晶体结构、合金成分和磁性的影响。研究凝固过程中外加磁场对颗粒晶体生长和织构形成的影响，制备出晶体结构和磁性一致性好的织构型球形合金粉末。研究织构型球形粉末/树脂基材料磁场下成型的复合材料的磁致伸缩效应和磁致应变行为，为发展高性能超磁致伸缩和磁致应变复合材料奠定基础。

球形单晶磁性粉末的制备对发展高性能磁致伸缩和磁致应变复合材料具有重要的意义。本项目在我们已有的研究基础上发展了一种球形单晶磁性粉末的制备方法，即通过液/固界面不润湿和异常晶粒长大机制制备球形单晶粉末，并利用磁性球形单晶粉末制备了高性能的超磁致伸缩复合材料。项目成功制备了(Tb, Dy)Fe2、CoMnSi和Ni-Mn-Ga合金微米尺寸的球形单晶粉末，掌握了制备三类磁性合金球形单晶粉末的核心技术以及相应的固体分散剂种类。通过磁场取向，制备了(Tb, Dy)Fe2/环氧树脂稀土超磁致伸缩复合材料，当(Tb, Dy)Fe2体积比为54%时，复合材料的饱和磁致伸缩系数在外加压力为10 MPa时达到1800 ppm，接近相同成分单晶块体材料的饱和磁致伸缩性能，在低、高频领域有重要的潜在应用。通过磁场取向，制备了具有b-c面取向的CoMnSi相/环氧树脂复合材料，其饱和磁致伸缩系数在室温达到1400 ppm；通过旋转磁场取向，成功制备了具有a-轴取向的CoMnSi相/环氧树脂复合材料，该材料的饱和磁致伸缩系数在室温达到2650 ppm，大于目前商用的Tb0.27Dy0.73Fe2稀土超磁致伸缩的性能，由于不含昂贵的稀土材料，有潜在的应用价值。项目的开展为发展高性能的超磁致伸缩复合材料奠定了坚实的基础。