Research On Structure And Properties Of Cu-Zr Amorphous Alloy Based On Hierarchical Clustering Method

In this paper,we investigate the clusters about the short range order of amorphous alloys using hierarchical clustering methods.By analyzing the data of the clusters generated by hierarchical clustering,we can obtain the glass-forming ability of different amorphous alloys.Combining the characteristics of hierarchical clustering,we can obtain a new way to form short range order for amorphous alloys.In Chapter 1,we introduced the history and development of amorphous alloys,the characteristics and formation principles of uncrystaline state,the development and application of machine learning in recent years,and the achievements of scientific research in materials science.In Chapter 2,we introduce the several methods of studying the structure of amorphous alloys and the basic principles of molecular dynamics simulation and softwares.We focus on the basic principles and implementation of hierarchical clustering in machine learning,and explain its feasibility in studying the microstructure of amorphous alloys.In Chapter 3,we obtain the data of Cu-Zr amorphous alloys by using molecular dynamics simulations.We get a lot of data of Cu-Zr amorphous alloy structure data by controlling the cooling rate and changing the compositions in Cu-Zr alloy.Using hierarchical clustering method,we obtain the clusters data of Cu-Zr amorphous alloys produced at different cooling rates.From analyzing the clusters structures at different cooling rates,we can conclude that the glass-forming ability will be weakened when the cooling rate is over 20K/ps.Using hierarchical clustering method,we obtain the clusters data of Cu-Zr amorphous alloy with different composition.From analyzing the clusters structures in different composition,we can conclude that amorphous alloys have the strongest glass-forming ability when the Zr atom number is between30%and 40%in Cu-Zr alloys.In Chapter 4,we increase the number of steps of hierarchical clustering to obtain the clusters of the first and second coordination shell that can be used to characterize the short range order of Cu₅₀Zr₅₀ amorphous alloy.We analyze the process of clustering"small clusters"into"large clusters"generated by hierarchical clustering.In the radial distribution functions of“small clusters”and“large clusters”,we find that the first coordination shell and the second coordination shell can construct at the same time.It’s different from the existing models that we must construct the first coordination first.