Effects of the location of a cast in the furnace on flatness of the solidification front in directional solidification

•The effects of location of a cast in the furnace on the solidification process were studied.•The criterion and the searching algorithm for the optimal location were presented.•The transverse temperature gradient is reduced by about 50% with the varying thickness mould at the optimal location.•The solidification time reduces notably for the cast with the varying thickness mould.

Many defects of single crystals are caused by the nonplanar solidification front. The transverse temperature gradient at melt–crystal interface results in nonplanar solidification fronts. The location of a cast in the directional solidification furnace affects heat dissipation and thus influences the transverse temperature gradient. This paper presents a criterion and a searching algorithm to find the optimal location of the cast for flattening the solidification front. A numerical simulation was employed for the verification of our method. Additionally, the effects of the size of the cooling device of the furnace on the optimal location, the transverse temperature gradient and the solidification time were discussed. The transverse temperature gradient is reduced about 50% without increasing much solidification time when setting the cast with a varying thickness mould at the optimal location. In addition, the optimal location is mainly influenced by the radius of the cooling ring.