基于原子团簇演变分析的非晶合金微纳结构热塑性成形工艺研究

With excellent thermoplastic forming ability and superb physical and chemical properties, metallic glasses are very suitable for preparing metallic micro/nanostructure, and have broad application prospect in micro electro mechanical system. However, the thermoplastic forming process will change the properties of metastable metallic glasses and the mechanism is far from understood, which severely constrains their practical application. Our previous studies have shown that thermoplastic forming process impacts the evolution of atomic cluster in metallic glasses and research from the perspective of atomic cluster structure will hopefully reveal the forming mechanism. In this project, the thermoplastic forming process is deeply investigated via molecular dynamic simulation and experimental method. The rheological behavior and surface/interface states of metallic glasses are studied in detail during thermoplastic forming and their effects on metallic glasses properties and forming process are discussed. The non-uniform distribution of atomic clusters and composition in metallic glasses is studied, which relates to the properties of forming parts. The theoretical model for forming is then established based on the evolution mechanism of atomic cluster. Further, the experimental research is conducted to verify the above theoretical research conclusions. The process parameters are adjusted according to the theoretical model to gradually optimize the micro/nanoscale thermoplastic forming process, so as to controllably prepare metallic glasses micro/nanostructure. Our work will contribute to a better understanding of micro/nanoscale thermoplastic forming of metallic glasses and promote the wider use of metallic glasses in China.

非晶合金具有优异的热塑性成形能力与独特的物理化学性质，非常适宜于制备金属微纳结构，在微机电系统中拥有广泛应用前景。然而非晶合金作为一种亚稳态材料，在热塑性成形过程中极易发生性质变化，其中机理还不清晰，这严重制约了它的广泛应用。我们前期研究表明成形过程改变了非晶合金内部原子聚集方式，从原子团簇演变出发对成形过程进行研究利于揭示其中机理。据此，本项目采用分子动力学模拟与实验研究相结合的方法，研究热塑性成形过程中材料流变特性变化与表界面状态，揭示其对材料性质与成形过程的影响机制；分析非晶合金成形过程中原子团簇与成分分布的均匀性，讨论其与成形件性质间的联系，建立基于原子团簇演变机制的理论模型；实验制备非晶合金微纳结构，依据成形理论模型逐步优化非晶合金微纳尺度热塑性成形工艺，实现非晶合金微纳结构可控制备。本项目的开展将为提升非晶合金微纳尺度成形工艺水平与推动我国非晶合金微纳结构广泛应用提供有力支持。

非晶合金具有优异的热塑性成形能力与独特的物理化学性质，非常适宜于制备金属微纳结构，在微机电系统中拥有广泛应用前景。然而非晶合金作为一种亚稳态材料，在热塑性成形过程中极易发生性质变化，其中机理还不清晰，这严重制约了它的广泛应用。从原子团簇演变出发对非晶合金热塑性成形过程进行研究，可以从理论层面揭示其中机理，优化工艺参数。本项目采用分子动力学模拟与实验研究相结合的方法，研究了热塑性成形非晶合金过程中材料表界面状态变化，揭示了其对材料性质与成形过程的影响机制，在微纳结构表面率先发现了表面分层结构，并使用表面张力波理论与晶面振动理论较完整地揭示了其变化现象，该机制使得非晶合金在纳米尺度呈现出一维有序性，它的发现颠覆了非晶合金各向同性以及内部原子排列无序的认知，极大促进了人们对低维非晶合金微纳尺度原子拓扑结构的理解，这将会对非晶合金微纳米加工工艺产生显著影响；研究了非晶合金与异种材料接触界面的演变方式，揭示了接触界面非晶化转变的分阶段二级相变特征，这修正了学术界对于界面非晶化过程相变属性的热力学理解；研究了热塑性成形过程中非晶合金的流变特性，建立了不同温度不同应变速率下非晶合金内部短程和中程有序结构的演变规律，从微观揭示了非晶合金在热塑性成形过程中的性质转变机制，为后续调控非晶合金性质提供重要理论支撑。掌握了非晶合金微纳结构成形过程中多种因素影响下内部原子聚合方式，明确其与成形件性质间的联系，建立基于原子团簇演变机制的成形理论模型，从本质层面理解了非晶合金热塑性加工性能，制备出了精细的微米尺度结构，并验证了相应模拟结果。本项目的开展为提升非晶合金微纳尺度成形工艺水平与推动我国非晶合金微纳结构广泛应用提供了有力支持。