Effect of Cooling Rates on Microstructures during Solidification Process of Liquid Metal Zn

Abstract

A simulation study was performed for the effects of six different cooling rates on microstructure during solidification of liquid metal Zn adopting molecular dynamics method. The pair distribution function g(r) curves, the total energy per atom, the bond-type index method and the cluster-type index method (CTIM-2) were used to analyze the variations of microstructure during the solidification process. The results showed that the cooling rate played a critical role in the microstructure transitions. As the cooling rate being 1×1014, 5×1013, 2×1013, 1×1013, 5×1012 K·s-1, the amorphous structures would be formed with 1551, 1541 and 1431 bond-types as the main body in the system. As the cooling rate being 1×1012 K·s-1, a part of crystal structure would be formed, in which the hcp and fcc basic cluster structures with 1421 and 1422 bond-types coexisted as the main body. At the same time, it was found that the glass transition temperature Tg would be decreased with the cooling rate slowing down.