Revisiting heat transfer analysis for rapid solidification of metal droplets

There are two major mechanisms controlling the rapid solidification processing (RSP) of metal droplets in spray forming. One is the external extraction of heat which is usually carried out through convective and/or radiatively heat transfer modes. The other is the internal heat conduction combined with the nucleation-controlled solidification kinetics. Heat transfer analysis for the RSP of a metal droplet is revisited through the two modelings with and without consideration of internal heat conduction. Two test problems with cooling rates of metal droplets of 10⁷ and 10³ K/s are studied. Results through comparing the two predictions, obtained separately by the two investigated models, lead to the conclusion that the heat transfer modeling has to consider internal heat conduction in the RSP of metal droplets even with small Biot numbers. Other factors which affect the prediction accuracy in the work are discussed.