Potential Function Construction And Structural Properties Of Pd-Cu-Si Based Amorphous Alloys

Amorphous alloys have many excellent properties such as short-range order,long-range disorder,isotropy,and metastable due to their atomic state.They have high thermal stability,chemical inertness,high toughness,and good corrosion resistance to be concerned.Pd-Cu-Si based amorphous alloy has become an ideal alloy system for studying amorphous structure,transformation,crystallization,and performance simulation due to its good thermal stability and simple component structure.Studying the structural evolution of Pd-Cu-Si based amorphous alloy during rapid solidification is of great significance for understanding its structural properties and glass forming ability.Since the liquid structure of amorphous alloys cannot be obtained in experiments,the study of the structure evolution during rapid solidification of amorphous alloys is generally carried out through molecular dynamics simulations based on empirical potentials.There is no corresponding empirical potential for the Pd-Cu-Si based alloy system,so this paper constructs the NN potential for the Pd-Cu-Si based amorphous alloy system based on the recently proposed Neural network(NN)potential function.Function,to carry out research on Pd-Cu-Si based amorphous alloy,the specific research content is as follows:(1)Based on the theoretical basis of the multilayer feedforward neural network,a NN potential function suitable for the Pd-Cu-Si alloy system is constructed,and the calculation accuracy of the NN potential function is verified.The verification results show that the NN potential function can accurately calculate the energy and force of the test set and the training set.The calculation error of the structure energy within the 95%confidence interval of the test set is?=13.56 me V/atom;for Pd-Cu-Si alloy the crystalline and amorphous structure of the system,and the NN potential function can accurately calculate the interaction in the structure.In comparison with the embedded-atom method(EAM)and first-principles calculation results,it is found that the calculation accuracy of the NN potential function is significantly better than the EAM potential function,and is close to the first-principles calculation accuracy degree.(2)Molecular dynamics simulation based on NN potential function has studied the structural characteristics of Pd₇₈Si₁₆Cu₆and the influence of Cu on its glass forming ability.The results show that in the liquid Pd₇₈Si₁₆Cu₆,it is found that Si clusters tend to have a low coordination number structure,while Pd clusters tend to have a high coordination number structure;as the temperature decreases,Si atoms tend to separate from each other,and Cu atoms tend to be separated.At the same time,the increase in the proportion of icosahedral-like clusters indicates that the structure system tends to be stable.From the network diagram of Si-Cu atoms,it is found that Cu atoms tend to form small clusters and fill the Si atom network gaps,so that the structural system becomes more dense.In the comparison of the structural properties of solid Pd₇₈Si₁₆Cu₆and Pd₈₀Si₂₀,it is found that the presence of Cu can make a complete Tricapped Trigonal Prism(TTP)<0,3,6,0>similar to a crystal centered on Si atoms ratio decreases,and the ratio of distorted TTP<0,4,4,0>increases,indicating that the crystallization process is inhibited and the system becomes more disordered;at the same time,the Voronoi index<0,0,12,0>represents the increase in the proportion of icosahedral clusters and icosahedral-like clusters represented by<0,2,8,2>and<0,1,10,2>indicates that the presence of Cu can improve the glass forming ability of the structural system.