Simulation Study for Effects of Cooling Rate on Microstructure Transition during Solidification of Liquid Metal Cu

A tracing simulation study has been performed for the effects on evolution of microstructures during solidification process of 50000 Cu atoms in liquid stater at different cooling rates by using the molecular dynamics method.The pair distribution function g(r)cures,the bond-type index method of HoneycuttAndersen(HA),the new cluster-type index method(CTIM-2)and visualization analysis have been used to analyze and study the evolution characterisitics of microstructures in the solidification process.It is found that a critical cooling rate is about 1.0×1013 K/s for transition from amorphous to crystalliine,and a crystalline and amorphous coexistence structure is formed finally in the system at this cooling rate.At the cooling rate of1.0×1014 K/s,the glass transition temperature TCis about 673 K.When the cooling rate is 4.0×1012 K/s,the crystallization starts from 673 Kin the system,and the crystal structures are formed mainly with the 1421and1422bond-types or fcc(12 0 0 0 12 0)and hcp(12 0 0 0 6 6)basic clusters.Meanwhile,it has been found that there are obvious effects of the cooling rate on the relative proportion of the fcc and hcp basic clusters,the lower the cooling rate is,the more the fcc basic cluster.