EFFECT OF SPIRAL DESIGN ON CRYSTAL ORIENTATION DURING SINGLE CRYSTAL GROWTH

Geometrical design of the spiral crystal selector can affect crystal orientation in the final single crystalstructure. to achieve a better understanding of conditions associated with the onset of crystal orientation in a spiralcrystal 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 abridgman type furnace. the crystal orientation of the samples was determined using electron backscattereddiffraction (ebsd) and optical microscopy. analysing the temperature field in the crystal selector revealed that, theorientation of growing dendrites against liquidus isotherm in the spiral selector was the reason for crystalmisorientation which differs in various selector geometries. increasing the take-off angle from 35° up to 45° increasesthe misorientation with respect to < 001 > direction. further increase of take-off angle greater than 45° will decreasethe crystal misorientation again and the efficiency of the selector to produce a single grain is decreased.