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

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 mm 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 ‹211› twin dendrite and a ‹100› twin-free dendrite grew in the range of undercooling from50 to 115 K. Dendrite growth velocity was also measured for different undercooling conditions. The growth velocity of ‹211› dendrites was slightly larger than that of ‹100› 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.