Molecular dynamics simulation of melt structure evolution during cooling process for lead on nickel substrate surface

The effect of heterogeneous substrates with micro-scale structure on the evolution of melt during the process of solidification is investigated, by molecular dynamics simulation on the structure evolution of lead melt on nickel substrate with a groove. During the cooling process, BCC structure forms firstly, and then FCC and HCP structures begin to form with the ratio reduction of BCC structure. Due to the existence of additional constraints by the substrate groove, the majority of the BCC structure inside the groove transforms into the metastable structure HCP, while the BCC structure outside the groove transforms into stable FCC structure mainly. At the end of the cooling process, a hybrid structure with FCC and HCP is formed from the lead melt, where FCC structure is dominant in the structure outside the groove, but HCP structure accounts for the majority in the groove.