Study On The Effect Of Thermal Pressure On Energy And Structure Of Metallic Glass During Quenching Processes

The phenomenon of aging changes the internal structure and mechanical properties of the metallic glass,and the aged metallic glass exhibits brittle fracture which severely limits its application.As a reverse process of aging,rejuvenation is an emerging and promising structural excitation method for metallic glass,however,the change of the energy and microstructure of rejuvenated sample is still unclear.In this paper,through molecular dynamics simulation,the high energy state metallic glass was prepared by thermal-pressure method,the effects of cooling rate,pressure and composition on atomic potential energy and volume were studied,and the changes of local atomic structure and mechanical properties were discussed.The main content of this paper is divided into three parts:?1?The effect of cooling rate on the energy and structure of Cu₅₀Zr₅₀ metallic glass during the quenching process was studied.It was found that the atomic potential energy and volume were significantly improved when the cooling rate was increased above 10¹³ K/s during the quenching process.In the process of relaxation at 300 K,the atomic potential energy and volume of the sample can maintain the original state well(except for the sample was prepared at the cooling rate of 10¹⁴ K/s has a tendency to decrease in the initial stage).About the research on structure,it was found that the fraction of polyhedron<0,0,12,0>which the coordination number is 12 and the bond-pair type 1551 got the minimum value at the cooling rate of 10¹³ K/s,and the metallic glass prepared at this cooling rate has the worst plasticity.?2?The effects of thermal-pressure on the energy and structure of Cu₅₀Zr₅₀metallic glass during each manufacturing stage?heating,equilibration and quenching?was investigated.It was found that loading pressure during the quenching stage can effectively obtain the metallic glass excited by the high energy state structure.In addition,the metallic glass obtained at 30 GPa still maintains a relatively high atomic potential energy after pressure release and relaxation,and the structure is the most densely packed.The Cu-centered polyhedron<0,0,12,0>reaches the maximum at30 GPa,this sample has the greatest plasticity.?3?The effect of thermal-pressure on the energy and structure of CuZr metallic glass with different compositions were studied.It was found that?PE_minin gradually changed from 0 to a nagetive value when the ratio of copper zirconium is more than1:1 at different cooling rates.About the change of structure,the composition of Cu₄₀Zr₆₀ obtained the densest structure at the pressure of 20 GPa among the five components.Through the radial distributiont function,the atomic clusters of of Cu₃₀^Cu₇₀ were transformed to a denser structure when the number of copper atoms increasing.