Solidification of Undercooled Ge_73.7Ni_26.3 Alloy Subjected to Sputtering-Deposition of Ni Clusters

Undercooled melt of Ge_73.7Ni_26.3 alloy sample floated on B₂O₃ melt was subjected to sputtering-deposition of Ni clusters on cooling to induce solidification. The initial temperature of solidification was 975 K. Its undercooling ΔT was 134 K with respect to the melting temperature of the primary phase Ge. On the cooling curve existed dual recalescences representing the transformation of the primary phase (Ge) and the eutectics (Ge+GeNi) respectively. But for the sample unsputtered, only a single exothermic peak presented on the cooling curve with the initial solidification temperature of 904K and undercooling of 205K. Careful observation of the microstructure proved that the Ge phase primarily formed in the sputtering experiment was now formed together with the formation of the eutectics in the experiment without sputtering.