Influence of a static magnetic field on the distribution of solute Cu and interdendritic constitutional undercooling in directionally solidified Al-4.5wt.%Cu alloy

•The Rank Sort method is applied to investigate the enhancement of the solute Cu.•The liquid/solid interface is observed by the means of 3D-CT technology.•Numerical simulation confirms that the dendrite refinement should be attributed to the solute enrichment. The 3D-CT technology and Rank Sort method are applied to investigate the influence of a static magnetic field on the morphology of the liquid/solid interface and the distribution of the solute Cu in directionally solidified Al-4.5wt.%Cu alloy. The results reveal that cells/dendrites refine, and the results of numerical simulation confirm that the magnetic field forms thermoelectric (TE) magnetic convection, resulting in the enrichment of the solute Cu in the liquid ahead of the liquid/solid interface. The cells/dendrites refinement under the magnetic field should be attributed to the increase of the interdendritic constitutional undercooling caused by the enhancement of the solute Cu.