Study On Atomic Structure And Its Correlation With Properties In Zr₅₀Cu₄₀Al₁₀ Metallic Liquids And Glasses

Amorphous alloys have excellent mechanical and physicochemical properties,which are new type materials with wide application prospect in the high-tech fields.There is a direct relationship between excellent properties of amorphous alloys and unique characteristics of microstructure.The study of microstructure of metallic glasses is of great significance for understanding the various properties of metallic glasses.In this paper,the Zr₅₀Cu₄₀Al₁₀ ternary alloys are studied.The molecular dynamics simulation method is used to study the evolution law of atomic structure and the relationship between the atomic structure and the thermodynamic and kinetic properties during rapid solidification,and investigate the effects of different cooling rates on the microstructure as well as the mechanical properties of amorphous alloys.Using pair distribution function,coordination number,Voronoi polyhedra,local five-fold symmetry and quasi-nearest atom structure analysis method,we study the evolution law of the atomic structure of Zr₅₀Cu₄₀Al₁₀ ternary alloys during rapid solidification process.Pair distribution function analysis shows that the melt structure becomes more compact and the short-range order is enhancedwith the decrease of temperature.We also found that there are chemical short-rang order between the heteroatoms,and there is a strong repulsive effect between Al atoms,which is more obvious in the supercooled liquid and amorphous state.The coordination number shows that the melt structure becomes denser with the decrease of temperature.The Voronoi polyhedra and local five-fold symmetry show that the content of the five symmetry structure increased significantly during the rapid solidification process.And quasi-nearest atom shows that there is spatial heterogeneity in the structure of the alloy with the decrease of temperature.We investigate the thermodynamic and kinetic properties,and the relationship between the atomic structure and the thermodynamic and kinetic properties of Zr₅₀Cu₄₀Al₁₀ alloy during rapid solidification.The potential energy analysis shows that the thermal stability of atomic structure is enhanced during rapid solidification.In addition,the investigation in the relationship between<NQ> and <Ep> at different temperatures shows that both of them meet the linear relationship,which suggests that <NQ> and <Ep> have a direct relationship.The kinetic properties show that the dynamic heterogeneity is enhanced with the decrease of temperature,and the diffusion coefficient has changed significantly at 1250 K,which indicates that the dynamic properties appear discontinuous changes as a result of the evolution of microstructure.We use pair distribution function,coordination number,Voronoi polyhedra,local five-fold symmetry and quasi-nearest atom structure analysis method tostudy the evolution law of the atomic structure of Zr₅₀Cu₄₀Al₁₀ amorphous alloys in different cooling rate.The pair distribution function shows that the bonding strength decreases gradually,the SRO decreases,and the density of the atomic structure decreases with the increase of cooling rate.The coordination number and quasi-nearest atom show that the coordination numbers decreases and the density of the atomic structure decreases with the increase of cooling rate.And Voronoi polyhedra and local five-fold symmetry shows that the structural stability of the amorphous alloy decreases gradually and the five symmetry is weaker with the increase of cooling rate.The stress-strain curve of Zr₅₀Cu₄₀Al₁₀ amorphous alloy during compression deformation is further analyzed.It's found that the mechanical property parameters of elastic limit,elastic strain,elastic modulus,compression strength and yield strength decreased significantly with the increase of cooling rate.In addition,the investigation in the relationship between <NQ> and yield strength shows that there is a simple linear relationship between them,which indicates that <NQ> and yield strength have a direct relationship.