Studying The Atomistic Strcuture Of Glass Forming Mechanism In ZrCu-Based Metallic Glass

As a new alloy material,metallic glass has attracted much attention.It has been a hotspot to study its glass forming mechanism from the microstructure.Because metallic glass does not have long-range order,some short-range structure factors are used to describe its microstructure characteristics,such as coordination number,atomic pair distances,cluster.In the study of metallic glass,solvent-solute model is usually used,and it is considered that this model provides important structural conditions for glass formation.In this paper,binary and multicomponent systems with different degrees of solvent-solute differentiation are selected from ZrCu-based alloy,and the structural factors in the glass formation are studied in detail by using synchrotron radiation technology and Reverse Monte Carlo?RMC?fitting method.Synchrotron radiation experiments are carried out on Zr₅₄Cu₄₆ and Zr₇₀Cu₃₀ metallic glass,and the three-dimensional model is obtained by RMC fitting method.The results show that there are little differences in atomic pair distances and coordination number.By further analyzing cluster information of the two samples,it is found that the main part of the cluster structure of the two samples is icosahedral or icosahedral-like clusters,and these clusters closely fill the space together with other clusters.It indicates that although Zr₅₄Cu₄₆ sample does not have obvious solvent-solute differentiating characteristics,it can also meet the structural requirements for glass formation.These icosahedral or icosahedral-like clusters are the key structural factors in the glass formation.This also indicates that although the solvent-solute model provides a favorable structural factor for glass formation,it is not a necessary condition for glass formation.Compared with binary Cu₆₄Zr₃₆ sample,quaternary Cu₃₄Zr₁₄Ti₃₆Pd₁₆ sample has higher glass forming ability?GFA?and weaker solvent-solute differentiation.It is found that the differences of coordination number,atomic pair distances and cluster are small.Based on cluster analysis,we calculate the atomic packing efficiency of the two samples and the regularity of the clusters.The results showed that the dense packing degree of quaternary sample is higher,which contributes to glass formation.The non-atomic occupied space of the both two samples and corresponding crystal are calculated.It is found that the values of free volume in the quaternary sample are smaller than the binary sample.This result is consistent with the fact that samples with higher GFA should contain less free volume.