Metastable phase formation with dendrite growth during laser-induced rapid solidification of Al59Ge41 sputtered thin films

Rapid solidification processes in amorphous Al59Ge41 thin films are induced by means of laser irradiation and within a wide range of pulse durations (50 mu s-500 ms). Results show that the metastable eutectic structure, formed by alternating lamellae of a hexagonal metastable phase and textured Al crystals, grows over a wide cooling rate interval. In the regime of ms pulses, additional Al dendrites, nucleated at Ge crystallites, are formed and allow concluding that this metastable hexagonal phase is favoured by small under-coolings.