Effect of the Coriolis force on the macrosegregation of aluminum in the centrifugal casting of Ti-Al alloys

Abstract

Within the framework of the ESA GRADECET project, experiments of directional solidification of cylindrical Ti-Al samples were conducted in hypergravity. The experiments were performed in a centrifuge with the apparent gravity (sum of centrifugal and terrestrial gravity) aligned along the cylinder centerline. 3D numerical simulations of aluminum macrosegregation in these samples are presented. A volume-averaging solidification model is used that accounts for centrifugal and Coriolis accelerations in a non-inertial rotating reference system. We compare the melt flow pattern and the macrosegregation formation under terrestrial gravity and under 20 g → centrifugation. The results show that the Coriolis acceleration, although very weak, breaks the symmetry of the thermosolutal convection, having an important impact on the final macrosegregation pattern. The macrosegregation is entirely modified in comparison with a sample solidified under terrestrial gravity conditions. Besides the aluminum segregation intensity increases with the centrifugation level.

Mesoscopic modeling of equiaxed and columnar solidification microstructures under forced flow and buoyancy-driven flow in hypergravity: Envelope versus phase-field model

“…Effective gravity in this process reaches up to tens of terrestrial gravity levels and buoyancy-driven convection of liquid is therefore strongly intensified. While the effect of centrifugation on the macroscale flow in the solidifying piece is fairly well known, mainly through process simulation [4][5][6], the influence of the strong convection on the growth of the solidification microstructure remains an open question.…”