Molecular Dynamics Simulation Of Coalescence Process Of Cu/Au Nanoparticles

With the rapid development of science and technology,nanoparticles(NPS)have attracted people’s attention for their fine physical and chemical properties,which have been widely used in many fields such as aerospace and microelectronics manufacturing.Different from the conventional materials,nanomaterials are affected by their huge specific surface area.The preparation process of nanomaterials is a very complex physical and chemical process.It is of great significance for the understanding of the mechanism of nano-nucleation and the improvement of the properties of materials to study this problem from two aspects of thermodynamics and kinetics,especially from the aspect of temperature characteristics.At the same time,the study of the relationship between microstructure and physical properties is helpful to the multi-scale and cross-scale study of material thermodynamic behavior.In this paper,the molecular dynamics simulations are employed to investigate the nanosintering of Cu/Au nanoparticle.By applying extremely high heating rate to the "two-particle" model which has been relaxed already,the change trend of various thermodynamic parameters and physical properties is analyzed,the phase transformation process and the change of microstructure and morphology of the material are explored,the mechanism of microscopic phase transition and atomic diffusion in the process of nanosintering are revealed.First,the nanosintering process of singlecrystal Cu nanoparticles is compared with that of polycrystal Cu nanoparticles.It is found that the melting temperature and the initial sintering temperature of polycrystal Cu system are significantly lower than that of singlecrystal Cu system.Then,the process of alloying of Cu/Au nanoparticle was discussed with the help of the RDF curve of the whole system,the shrinkage ratio and the sintering neck size.The initial sintering temperature of three different systems(Cu,Au and Cu/Au alloys)and the micro-mechanism were also discussed.At the same time,it is found that the difference of melting point between nano-gold and nano-copper leads to the phenomenon that the Au atoms diffused through the outer area of the sintering neck before the nanoparticles were fused into one sphere.Finally,it is found that the initial sintering temperature of Cu/Au nanosintering decreases with the decrease of heating rate.