M. Ghanbari, M. R. Aboutalebi, S. G. Shabestari,
Volume 11, Issue 2 (6-2014)
Abstract
Geometrical design of the spiral crystal selector can affect crystal orientation in the final single crystal
structure. To achieve a better understanding of conditions associated with the onset of crystal orientation in a spiral
crystal selector, temperature field was investigated using three-dimensional finite element method during the process.
Different geometries of spiral crystal selector were used to produce Al- 3 wt. % Cu alloy single crystal using a
Bridgman type furnace. The Crystal orientation of the samples was determined using electron backscattered
diffraction (EBSD) and optical microscopy. Analysing the temperature field in the crystal selector revealed that, the
orientation of growing dendrites against liquidus isotherm in the spiral selector was the reason for crystal
misorientation which differs in various selector geometries. Increasing the take-off angle from 35° up to 45° increases
the misorientation with respect to <001> direction. Further increase of take-off angle greater than 45° will decrease
the crystal misorientation again and the efficiency of the selector to produce a single grain is decreased.
