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 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.
Highlights
Titanium aluminum alloys have been studied during the last 30 years due to their low density and high resistance in high temperature environments, making them a very good candidates for automotive and aerospace applications
The results show that the Coriolis acceleration, very weak, breaks the symmetry of the thermosolutal convection, having an important impact on the final macrosegregation pattern
Ramachandran et al [2] performed numerical simulations attemping to emulate the liquid thermodriven convection that takes place in a centrifuge-based Bridgman crystal growth configuration, reporting that the Coriolis acceleration played a stabilizing role in cases where the centrifugal acceleration was parallel to the thermal gradient
Summary
Titanium aluminum alloys have been studied during the last 30 years due to their low density and high resistance in high temperature environments, making them a very good candidates for automotive and aerospace applications. 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.
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