ZrCuAl系非晶合金结构不均匀性与剪切带关系的研究

The excellent properties of amorphous alloys have made them new advanced materials whose applications are wide. However, due to the microstructural heterogeneity, amorphous alloys do not possess dislocations, grain boundaries and other defects. This makes shear bands be the main deformation form of amorphous alloys, so their plasticity is very poor at room temperature, restricting their industrial applications. In this project, it will be mainly focussed on the study of microstructural heterogeneous distributions on the temperature and time window, in order to reveal the relations between the microstructural heterogeneity and shear bands. A series of ZrCuAl amorphous alloys will be selected to characterize the disorder distributions of atomic structure on the temperature and time window through the combination of molecular dynamics simulations and experiments. Under different processing parameters, such as time, temperature and cyclic loading, amorphous alloys will show different shear band characteristics, where the effects of microstructural heterogeneity on the nucleation, propagation and interaction of shear bands will be clarified. The nucleation sites and propagation directions will be predicted, and the quantitative relation between microstructure heterogeneity and deformation units will be established. Through these studies, it will be helpful for ensuring the reliability and developing new amorphous alloys for engineering applications.

非晶合金具有很多的优异性能，使得它成为一类应用前景广泛的新型先进材料。但由于微观结构的特殊性，非晶合金不具备位错、晶界等缺陷，使得剪切带是非晶合金在室温下变形的主要形式，所以非晶合金在室温下塑性非常差，制约着其工业化应用。本课题主要通过调整非晶合金微观结构在温度和时间窗口上的不均匀性分布，旨在查明微观结构异质性和剪切带之间的内在关联性。以ZrCuAl系非晶合金为研究对象，通过分子动力学模拟和实验相结合的手段，将系统表征非晶合金中原子结构在温度和时间窗口上的不均匀性分布。在不同加载条件下，比如时间、温度和循环加载，表征非晶合金不同的剪切带特征，查明结构不均匀性对非晶合金剪切带形核、扩展和相互作用的影响。预判剪切带形核点与扩展方向，建立微观结构异质性和形变单元的定量关系。为改善非晶合金在工程应用中的稳定性以及发展新型非晶合金奠定基础。

本项目根据申请书中的研究规划对非晶合金微观结构与剪切带关联进行了系统研究。基于团簇体积膨胀和收缩程度，从整体微观结构上分辨和量化了非晶合金的微观结构异质性；建立了非晶合金变形过程中的剪切转变区和微观结构不均匀性的关系；提出并建立了调控非晶合金剪切带的新判据，为非晶合金中形成剪切环从而引起均匀变形提供微观结构支撑；直观给出了非晶-晶体金属复合材料界面处位错和剪切单元相互作用原子结构图像，并通过压痕引入缺口新方式改变剪切带形成位置，达到了提高强化效果并改善塑性变形能力的目的。相关结果发表SCI收录论文16篇，中文综述1篇，其中包含Journal of Materials Science & Technology、 Journal of Alloys and Compounds 、Materials and Design 、Intermetallics、The Journal of Chemical Physics等期刊。国际性学术会议1次，国内会议4次。