非晶合金弛豫脆化与原子团簇结构的关联性研究

The amorphous alloys have been accepted as an ideal green energy-saving materials being used in the field of power transmission and distribution, electronic information and new energy vehicles. However, the heat treatment before use has resulted in structure relaxation, leading to severe embrittlement. The embrittlement has been proved to decrease its excellent soft-magnetic properties and constrict the following machinability. As the relaxation is correlated to its micro-structure, the intuitive methods to characterize the micro-structure have not been revealed, so the progress on the mechanism study of relaxation embrittlement has been constricted. This has been treated as one of the frontier scientific problems, which needs to be solved urgently. Our team’s previous research has shown that three-dimensional reconstruction electron microscope can characterize the cluster structure and their connections. This technique offers a chance to study the mechanism of relaxation-induced embrittlement. The relaxation-induced embrittlement Zr50Cu40Al10 and relaxation-induced non-embrittlement Zr60Cu30Al10 alloy systems has chosen as the research object. The in-suit three-dimensional reconstruction electron microscope and large-scale atomic/molecular massively parallel simulator are used to observe the evolution of atomic clusters and their connections, and to study the correlation of relaxation-induced embrittlement and cluster structure. Through these researching, the mechanism of relaxation-induced embrittlement correlated to cluster structure will be established, which can provide the theoretical basis for the solution of relaxation-induced embrittlement in the application field.

非晶合金是应用于输配电、电子信息、新能源汽车等领域理想的绿色节能材料之一。但非晶合金退火产生的结构弛豫导致脆性增加，降低了其优异的软磁性能且制约了后续可加工性。非晶合金的弛豫与微观结构密切相关，但由于缺乏结构的直观表征方法，制约了非晶合金弛豫脆性的微观机理研究，是该领域亟待解决的前沿科学问题之一。本项目组前期研究发现，采用电子显微学三维重构技术，能够表征出非晶合金的微观团簇结构及其连接信息。这给研究弛豫脆化机理带来契机。本项目拟以弛豫脆化的Zr50Cu40Al10和弛豫不脆化的Zr60Cu30Al10非晶合金作为研究对象，采用原位电子显微学三维重构技术和大规模分子动力学，观测弛豫过程中原子团簇结构及其连接的演化，解析团簇结构与弛豫脆化的关联性。通过这些研究，建立结构与弛豫脆化模型，为解决非晶合金应用的弛豫脆化问题提供理论依据。

如何表征并建立非晶合金的物理结构模型，一直是材料学和凝聚态物理领域最为关注的核心问题之一。本项目重点采用电镜三维重构技术和大规模分子动力学模拟等方法，系统地表征出ZrCuAl系非晶合金的空间广延拓扑团簇结构。项目首次实现了360°非晶合金微观结构的实验表征，观测到二十面体等团簇形貌、团簇点、线、面连接、团簇类型及尺寸等一系列信息，获得了非晶合金三维结构信息及微观结构的不均匀性特征，为现有非晶结构预测模型提供了直观的实验证据。基于团簇理论，研究了Zr60Cu30Al10和Zr50Cu40Al10非晶合金弛豫脆性差异的微观结构机理，源于Zr50Cu40Al10合金拥有质脆准晶结构的二十面体团簇含量更高所致。基于团簇对粘度的影响理论，FeSiB等典型铁基非晶的母合金和非晶合金在约1400℃存在的液液相变现象，被采用DSC、第一性原理等方法深入研究，该液液相变本质源于Fe2B团簇转变为Fe3B团簇，该转变结束后获得理想均一熔体。这些研究工作为观测非晶合金微观结构开辟了新的技术路径，为通过调控团簇结构调控非晶合金的宏观物理性能提供了基础条件，为认知团簇结构与物理性能关联提供了理论参考。