铁基非晶软磁合金过冷液体相稳定性与大块金属玻璃形成能力的关系研究

Iron-based amorphous alloys and their nano-crystalline materials have been used in many applications, such as transformer core, by taking advantage of their excellent soft magnetic characteristics over that of traditional soft magnetic alloys. However, the average glass-forming ability of this kind of materials limits their potential applications. Our ability to solve the development of bulk amorphous Fe-based soft magnetic alloys can benefit from increased understanding of their glass-forming ability (GFA). To pave the way for preparation of iron-based bulk amorphous alloys with superior glass forming ability, we intend to probe the structure of the metallic liquids and the microscopic mechanism of liquid phase transition kinetics during the cooling of metallic melt and to unveil the nature of GFA in Fe-based amorphous soft magnetic alloys.Studies will be carried out in these following aspects: 1) We will apply the induction heating aerodynamic levitation suitable for synchrotron scattering experiments. This containerless environment allows access of deep supercooling for metallic liquids. The evolution of atomic-scale microstructure of the alloy samples during liquid-to-liquid transition and liquid-to-crystalline transition will be detected by time-resolved synchrotron scattering technique upon heating and cooling. 2) In-situ diffraction and small angle scattering will be applied to study the crystallization process of Fe-based amorphous soft magnetic alloys to reveal nanoscale chemical-magnetic correlations. 3) The magnetic properties of Fe-based magnetic alloys will be characterized, notably with magnetic small angle neutron scattering, and correlated with the atomic and nanoscale structures. This study will shed light for the research and development of novel bulk amorphous Fe-based amorphous soft magnetic alloys.

铁基非晶合金及其纳米晶材料的软磁性能大大超越了传统软磁合金，已经被应用于磁性合金各个领域，如非晶合金变压器芯。但有限的非晶形成能力制约了其应用前景。研究铁基非晶软磁合金的非晶形成能力的物理本质是解决大尺寸样品制备的可行途径。本研究旨在探索铁基非晶软磁合金的高温熔体冷却过程中液态相变动力学的微观机制为揭示合金非晶形成能力的物理本质，实现大尺寸铁基非晶软磁合金样品的制备。本研究将从以下方面展开：1）探索气动悬浮电磁感应快速加热装置在同步辐射散射上的应用，为合金液体相变过程研究提供无容器化环境，确保合金液体的过冷度的获得；2）利用时间分辨的同步辐射散射等手段，原位检测样品加热和冷却过程中，液态-液态相变及液态-结晶转变过程原子尺度微观结构的演变3）利用原位小角中子散射研究超铁基非晶软磁合金结晶过程中纳米尺度结构与磁畴结构的关联性。本研究将为新型大尺寸铁基非晶软磁合金的研发提供重要参考。

铁基非晶合金及其纳米晶材料的软磁性能大大超越了传统软磁合金，但有限的非晶形成能力制约了其应用前景。本项目主要使用一系列原位测试手段，研究了铁基非晶软磁合金的高温熔体在冷却过程中液态相变动力学的微观机制和大块铁基非晶软磁合金样品的制备等。该项目的主要成果如下：1）探明了非晶合金中潜在相变过程的微观机制，首次发现非晶合金热分析过程中的异常放热峰（AEP）伴随着液态-液态相变和重入过冷液体现象；2）研究了两元锆基金属玻璃原子尺度和纳米尺度范围内结构与玻璃形成能力之间的相关性，此研究对金属玻璃的成分设计和性能调控具有指导性的作用；3）利用超高压电子显微镜(HVEM)在原子尺度上原位观测了两种具有不同玻璃形成能力的三元锆基金属玻璃过冷液相区的晶化行为，揭示了具有优异玻璃形成能力的Zr46Cu46Al8合金的非经典晶体生长模式；4) 研究了加载压应力对Ca40Mg25Cu35金属玻璃晶化过程的影响。此研究对于金属玻璃的结晶过程控制具有指导性的作用；5）研究了具有不同热物性行为的铁基金属玻璃在超过冷液相区加热和保温过程中结构演化动力学问题，发现具有较好玻璃形成能力的大块金属玻璃(Fe0.72B0.24Nb0.04)95.5Y4.5在结晶之前出现异常放热峰，并观测到重入超过冷液体行为，在 AEP 某一临界温度发现高度关联结构的隐藏非晶相，在较高温度下重进入低关联结构的无序相中；6）以玻璃形成能力优异的五元锆基非晶合金为原型，原位研究了非同寻常的多步结晶过程及类G-P区的沉淀析出过程，该异常结晶路径为非晶多型性相变、化学相分离、无序亚稳相的形成与最终结晶阶段；7）以磁学性能优异的软磁非晶合金nanomet为研究对象，利用小角中子散射研究了软磁非晶合金nanomet的纳米尺度晶化行为和磁结构演变，揭示了不同的退火温度和退火时间对软磁非晶合金的纳米晶以及磁畴结构的影响；8）开发了一种成本低廉且适用热压打印的非晶合金材料，已申请发明专利并获得授权。本项目的研究成果为新型大尺寸铁基非晶软磁合金的研发提供了重要参考。