On the significance of surface tension driven flow in floating zone melting experiments

The predominance of the surface tension driven (Marangoni) flow over the buoyancy driven free convection for small zone lengths in electron beam floating zone melting of doped molybdenum rods is pointed out. The observed different patterns of microsegregation and the critical conditions of their occurrence, i.e. B-cores below a critical zone length of l_c = 3.5 mm and B-striations above this value, are shown to be in qualitative agreements with theoretical predictions made from convection models.