Lamella structure formation in drop-tube processed Ni-25.3 at.% Si alloy

Rapid solidification experiments have been performed on an Ni-25.3 at.% Si alloy using drop tube techniques. The dominant phase formed is found to be Ni25Si9, with Ni31Si12 and く1-Ni3Si also being present. SEM and TEM analysis revealed a novel eutectic structure consisting of lamellar of metastable Ni25Si9 and く1-Ni3Si, the width of these being around 200 nm and 20 nm respectively. This result indicates that there is a possible eutectic reaction for the Ni25Si9 and く1-Ni3Si phases existing in the metastable phase diagram.