铁磁性非晶合金宏观塑性的电子结构起源

Despite of their excellent mechanical and soft-, hard- magnetic properties, ferromagnetic amorphous alloys always display a very poor plasticity, which prevents them from wide application in our daily lives. Our previous studies show that electronic density of state (DOS) on the Fermi level is closely related with the plasticity of metal. Thus, in this project we focus on improving the plasticity of ferromagnetic amorphous alloys based on optimizing the alloy composition, guided by tuning the bonding state of system: (1) varying the mechanical properties of system by alloying different elements; (2) using synchrotron high-energy X-ray diffraction and neutron scattering to investigate atomic structure and dynamic behavior of glass and melts of alloys, using nuclear magnetic resonance (NMR) and X-ray photoelectron spectroscopy (XPS) to investigate the bonding state of their glass state; (3) based on the systematic investigations of atomic and electronic structure, we intend to find the correlation between the bonding state and the atomic structure and dynamics. This will help us to understand fracture mechanism of ferromagnetic amorphous alloys from electronic structural point of view, allowing the design of novel alloy systems which process large deformation-ability. Our studies might lead to a map for understanding the origin of plasticity and the search of amorphous alloys with high toughness.

铁磁性非晶合金虽然拥有优异的力学和软、硬磁性能，但是宏观塑性差，这极大的限制了其在日常生活中的广泛应用。申请人前期研究表明金属材料费米面上电子态密度与宏观塑性密切相关，因而本项目申请人计划通过合金元素掺杂调控体系键态特征，改善铁磁性非晶合金的宏观塑性：（1）合金元素掺杂对铁磁性非晶合金力学性能的调控；（2）引入同步辐射高能X射线衍射和中子散射技术结合悬浮技术对液态、玻璃态的结构和动力学行为进行研究，并利用固体核磁共振技术结合X射线光电子能谱对玻璃态的电子态密度分布进行研究；（3）基于以上原子、电子结构的系统研究，建立电子结构与原子团簇结构、液态动力学二者之间的内在联系，从电子结构角度揭示铁磁性非晶合金断裂机理，探索新型大塑性铁磁性非晶合金。该项目为我们认识非晶合金的塑性起源，寻求韧性非晶合金提供了可行的指导蓝图。

为了改善铁磁性非晶合金宏观塑性差的严峻问题，从微观层面认识非晶合金塑性的电子结构起源，申请人引入同步辐射高能X射线衍射、小角散射、三维原子探针技术结合第一性分子动力学模拟，系统研究了合金成分对非晶合金本征塑性或脆性的影响：(1) 探讨了3d Ni元素的引入对Fe-B-Si-P-Nb体系能带结构的改变，初步建立结构模型探讨金属键的柔顺性对非晶合金宏观塑性的影响；(2) 研究了Cu元素的添加对Co(Fe)-B-Si-Nb合金体系原子尺度结构和微观力学响应的影响，给出了化学作用对非晶合金蠕变行为影响的微观解释；(3) 研究了4f稀土元素的添加对Fe-Nb-B非晶合金室温塑性和热塑性成型能力的调控。申请人还利用固体核磁共振结合第一性原理计算对非晶合金形成体系费米能级电子态密度、电荷分布、原子间距、短程和中程序结构进行了表征，提出了从原子、电子层面设计非晶合金的新思路。