软磁非晶合金多形相变结构模型建立及机理研究

The proposed project is targeted at the research questions on the establishment of structural model and its mechanism of polymorphous phase transition of soft magnetic amorphous alloy based on the previous research works that tensile stress annealing at 400 °C could significantly improve the soft magnetic property of the FeCuNbSiB amorphous alloy. With the low temperature annealing of tensile stress of amorphous alloy, the microstructure of soft magnetic amorphous alloy will be measured by using XRD, AFM, MFM, SEM and TEM techniques. The microstructural evolution of amorphous phase induced by low temperature annealing will be further measured by using high energy, high precision synchrotron radiation XRD technique for different temperatures, stresses, and samples. The measurement will be focused on the changes in the atomic structure within the medium range (i.e., 10-14Å). A structural model will be constructed and analyzed by combining anti-Monte Carlo (RMC) simulation and high precision synchrotron radiation XRD data fitting, and then used to explore the structural characteristics of polymorphic phase transition of amorphous alloys induced by the low temperature annealing of tensile stress. The project will help understand the underlying mechanism of polymorphic phase transition induced by the low temperature annealing of tensile stress and enrich the theory of polymorphic phase transition of amorphous alloy. The project will further help solve the problem of amorphous embrittlement of soft magnetic amorphous alloy and provide theoretical basis for the development of soft magnetic amorphous alloy materials with excellent properties.

本项目以前期400°C张应力退火FeCuNbSiB非晶合金的效果为基础提出科学问题，从非晶合金张应力低温退火入手，利用XRD、AFM、MFM、SEM、TEM技术测试非晶合金材料的微观结构，采用高能量、高精度同步辐射XRD技术原位跟踪测试系列温度、系列应力和系列组分样品的张应力低温退火诱导非晶合金多形相变的微结构演变过程，重点关注是中程（10-14Å）范围内原子结构变化，结合反蒙特卡罗（RMC）模拟、拟合高精度同步辐射XRD数据，构建结构模型进行计算分析，掌握张应力低温退火诱导多形相变非晶合金的结构特征。以期通过项目实施，揭示张应力低温退火诱导多形相变的机理，丰富非晶多形相变理论，为进一步解决非晶合金退火脆化问题、研发具备优异特性的非晶合金材料提供理论基础。

Fe基非晶纳米晶合金具有优异的软磁性能，可广泛应用于电力电子器件领域，但是合金退火脆化限制了应用。为此本项目从张应力低温退火工艺着手，建立了退火工艺条件与FeSiB(C)、FeSiB(P)、FeCuNbSiB、FeSiBPCCu(Nb)、FeCuSiBNbMn和FeCuSiBNbMo等非晶合金的软磁性能的关联，分析了张应力低温退火工艺条件对合金宏观应变、磁各向异性的影响规律。研究了张应力退火中非晶合金多形相变的微观结构演变及其与软磁性能的关联。通过高能量、高精度原位同步辐射XRD分析技术揭示了张应力退火过程中非晶多形相变及其宏观应变、微观应变、晶格各向异性和磁各向异性的演变，发现应力退火诱导的a-Fe(Si) 纳米晶晶粒在平行于张应力方向和垂直于张应力方向的衍射峰位间距增大, 具有正的和较大的结构各向异性, 应力退火后样品的结构各向异性作为残余应变释放。上述研究结果为解决非晶合金退火脆化和提高软磁性能提供了新思路。