Spurious grain formation due to Marangoni convection during directional solidification of alloys in µ-g environment of International Space Station

•Influence of Marangoni convection on movement and rotation of fragmented dendrites is simulated.•Strength of convection depends on size and location of the pore relative to the mushy zone.•Marangoni convection was found strong enough to force the rotation of broken-off side arms.•Marangoni convection can be considered as a source of microstructural inhomogeneity.