A splat formation model has been developed based on the classic nucleation theory accounting for heterogeneous nucleation kinetic and crystal growth to predict the nucleation temperature and grain size distribution. The predicted grain size distribution has been compared with experimental data for molybdenum (Mo) splats on different substrates. The influence of the substrate material, interfacial thermal contact resistance, and wettability on the nucleation, grain size distribution, and rapid solidification process has been investigated. Based on scaling analysis, the nucleation delay and solidification times have been derived and compared with simulation results. (C) 2004 Elsevier Ltd. All rights reserved.