Effects of Cooling Rate on the Solidification Process of Pure Metal Al: Molecular Dynamics Simulations Based on the MFPT Method

Isothermal solidification process of pure metal Al was studied by molecular dynamics (MD) simulation using EAM potential. The effects of different cooling rates on the isothermal solidification process of metallic Al were studied. Al was first subjected to a rapid cooling process, and then it was annealing under isothermal conditions. The mean first-passage times (MFPT) method and Johnson-Mehl-Avrami (JMA) law were used to qualify the solidification kinetic processing, and the nucleation rate, critical nucleus size, Avrami exponent and growth exponent of grains were calculated. Results show that the nucleation rate and critical size decrease as the cooling rate increases. Also, an increase in the cooling rate leads to the increase of grain growth rate. At all investigated cooling rates, nucleation and growth processes are in the typical three-dimensional growth mode.