Surface energy enhanced crystallization kinetics in ultrathin foils of amorphous alloys

A thermodynamic description of Crystallization in amorphous thin foils is presented. The specimen geometry is described by a wedge and the total driving force for phase transformation is expressed in terms of volume. surface and interfacial free energies. At low specimen thickness, the driving force is strongly enhanced by the surface free energy and approaches a constant value at large specimen thickness which is determined by the volume free energy. Energy minimizing crystal orientation results in equiaxed crystals at low specimen thickness. The classical theory of phase transformation is used to calculate the crystallization rate. The results of the present work show that the crystallization rate increases strongly at low specimen thickness which is in qualitative agreement with experimental results.