Critical structural invariant during high-pressure solidification of copper

Molecular dynamics simulation (MD) has been conducted to investigate the pressure effect on microstructure of copper during rapid solidification. The pressure increases the onset temperature (T-c) of nucleation but decreases the energy of atoms and the lattice constant of the final face-centered cubic crystal. Before temperature decreases to T-c the average coordination number (ACN) of atoms and the percentage of topologically close-packed atoms (P-TCP) increase, while the number of types of the largest standard clusters (K-LaSC) decreases and that of the topologically close-packed (K-TCP) atoms is about the same. Interestingly they are pressure-independent constants at T-c, with K-LaSC = 3300, ACN =13.08, P-TCP = 18.3%, and K-TCP = 33 in the super-cooled copper.