Faceted dendrite growth of silicon from undercooled melt of Si-Ni alloy

Abstract

Two-dimensional faceted dendrite growth of silicon from undercooled melt of Si-6 wt%Ni alloy was experimentally investigated, in which molten alloy film from 10 to 20 μm in thickness was undercooled up to 115 K and growing dendrites were observed in situ. Both the in situ observation of dendrite morphology and the EBSP crystallographic analysis for solidified samples showed that both a 〈2 1 1〉 twin dendrite and a 〈1 0 0〉 twin-free dendrite grew in the range of undercooling from 50 to 115 K. Dendrite growth velocity was also measured for different undercooling conditions. The growth velocity of 〈2 1 1〉 dendrites was slightly larger than that of 〈1 0 0〉 dendrites. It is concluded that the upper envelope of the data provide the correct dendrite growth velocity and it is compared with that obtained by phase-field simulations. Growth velocity in both follows power relationships to undercooling and the linear kinetic coefficient is estimated to be 0.01 m/s K. © 2006 NIMS and Elsevier Ltd.