Study Of The Correlation Between Structure And Physical Properties In Metallic Glasses By Computational Simulation

Amorphous alloy(AA),also known as metallic glass(MG),is a typical kind of atomic glass system formed by metallic bonds.The relatively simple atomic structure of MG makes it a perfect model to study the basic physical problems in glasses.The excellent mechanical,physical and chemical properties of MG also provide bases for its application in various fields.Therefore,the study of MG is vital important for both scientific research and real-world application.One of the current focal issues in the research of MGs is whether there is a unified model to describe the atomic structure of various kinds of MGs and establish an effective correlation between the structure and its related properties.Due to the limitations of experinental characterization methods,it is hard to obtain the atomic packing scheme of MGs in experiment.Computational simulation at atomic scale has become an important method in characterizing atomic structure of MG and exploring the correlation between its structure and physical properties.Firstly,the ? relaxation of two kinds of binary metallic glasses La65Ni35 and La65Al35 are studied by classical molecular dynamics(MD).Through MD-simulated dynamical mechanical analysis,the results indicate ? relaxation in La65Ni35 is stronger than La65Al35 which is consistent with experimental observation.In the two systems,Ni has the largest no-affine displacement during periodic shearing.It has distinct relaxation behavior formed by cooperative motion between second-neighbor Ni atoms and can be well distinguished from La and Al;Combining ab initio molecular dynamics and electronic structure analysis,we find out the difference of relaxation behavior in the two systems is due to the different element types,local atomic structure and chemical environments.Next,we introduce ? which corresponding to the mean square atomic vibrational amplitude under energy equipartition.The linear correlation between ? and shear modulus is established through MD simulation of various kinds of glass-forming systems.In the meantime,? shows a good correlation with low temperature dynamics,local atomic structure and shear transformation zone.Its novel properties may help us build the connection between structure and physical properties in MGs.