The Molecular Dynamics Simulation Of Microstructure And Dynamics In Zr₆₅Cu₃₅ Amorphous Alloy

In this paper, we study the microstructure, dynamics properties and the relationshipbetween them. And we also study the relaxation of metallic glass by using moleculardynamics simulation.LFFS (local five-fold symmetry) is used to characterize the short range order of ZrCuamorphous alloy. It is proved that the degree of LFFS increases with the decreasing of thetemperature. And the dynamics properties during the liquid-glass transition is also studied.We find that the lower the temperature, the longer β relaxation, and the smaller theself-diffusion coefficient which follows different laws with the temperature decrease. Anddynamic heterogeneity exists in metallic glass and supercooled liquid, in addition, thedegree of dynamic heterogeneity increases with the increase of temperature. Besides, theatoms with d5≤0.3have quicker dynamics behavior, and the atoms with0.7≤d5≤1haveslower dynamics behavior, while the atoms with0.3<d5<0.7have no significant influenceon the whole dynamics, which shows that the structure with high five-fold symmetryslows its dynamic behavior.The change of storage modulus E’ and internal friction tanδ during the heatingprocess is further analyzed. It’s found that beta relaxation is in the form of excess wing onthe internal fiction curve. What’s more, The influence of test frequency on relaxationbehavior is also researched, and find that there exists the transition from β relaxation to αrelaxation below the glass transition temperature. Isothermal annealing at730K (below Tg)and850K (above Tg) are respectively performed on the amorphous model. And then westudy the dynamic mechanical properties of the two annealed model during the heatingprocess, then compared to the unannealed model. According to the results, annealing at730K induces E’ a significant increase and internal friction a obvious decrease, whichmeans the decrease of the β relaxation intensity. However, after annealing at850K, theinternal friction at low temperature increases significantly, meaning the intensity of βrelaxation improved to a certain extent, which provides the mentality for improving themechanical properties of Zr65Cu35amorphous alloy.