Simulation study of the effets of various cooling rates on evolution properties of micro-cluster structure during solidification processes of liquid metal Cu

A simulation study has been performed on the effects of microstructral transition during solidification process of 50000liquid metal Cu atoms at three different cooling rates by adopting the molecular dynamics method and Quantum Sutton-Chen many body potential.The pair distribution function g(r)cures,The bond-type index method of Honeycutt-Andersen(HA),the cluster-type index method(CTIM-2)and visualization anaysis have been used to analyse and study the evolution properties of micro-cluster configurations during solidification processes.It is found that the critical cooling rate is about 1.0×1013K/s for transition from amorphous structrue to crystal structure,the crystal and amorphous mixed coexistence structures are formed finally in the system when the cooling rate is 1.0×1013 K/s.At the cooling rate of 1.0×1014 K/s,amorphous structures are formed mainly with the 1551、1541、1532 and 1431bondtypes,and the glass transition temperature Tcis about 673K.At the cooling rate of 4.0×1012 K/s,Thecrystallization starts from 673Kin the system,and the crystal structures are formed mainly with the1421and 1422bond-types or FCC(12 0 0 0 12 0)and HCP(12 0 0 0 6 6)basic clusters consisting of the two bond-types.Espeically,FCC(12 0 0 0 12 0)basic cluster consisting of 1421bond-type occupies a dominant position in crystal-growth and the forming processes of micro-cluster structures.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 for the system containing of metal Cu,the lower the cooling rate is,the more the FCC basic cluster and cluster structure making up of FCC cluster.