Crystal nucleation in undercooled liquid zirconium

Electromagnetic and electrostatic levitation are applied to undercool melts of pure Zr. Each sample is undercooled approximately 100 times and the distribution functions of undercoolings are determined. They are analyzed within a statistical approach of classical nucleation theory. Despite large undercoolings the analysis predicts heterogeneous nucleation in electromagnetic levitation. Electrostatic levitation leads to an increase of average undercooling and the statistical analysis indicates that the undercoolings approach the limit as given by homogeneous nucleation.