ON THE GROWTH OF (110) TWIN DENDRITES IN UNDERCOOLED GE

The microstructures of [110] twin dendrites were studied in detail. It was found that the periphery surfaces of the dendrite are all {111} planes. A [110] twin dendrite model was constructed to explain the growth morphology. The model predicts the absence of branching except in the initial stage, which has indeed been observed experimentally. From the model, it turns out that the [110] growth is in fact a combination of two [211] twin dendritic growths if the latter can maintain their coherency. Finally, the [110] to [211] dendritic transition is attributed to the break-up of the coherent growth of the two [211] dendritic growths.