Revealing growth mechanisms of faceted Al2Cu intermetallic compounds via high-speed Synchrotron X-ray tomography

This study used high-speed synchrotron X-ray tomography to image the growth of Al2Cu intermetallic compounds in 4D (3D plus time) during solidification Al-45wt%Cu alloy. Two categories patterns (basic units and dendrites) are identified. Basic elongated rods whose cross-section L, U or hollow-rectangular shapes. The transition from L pattern finally shaped morphology is observed. Faceted dendritic include equiaxed prism columnar dendrites. Self-repeated layer-by-layer stacking basic (such as particles) proposed a governing mechanism for faceted orientation morphologies these strongly influenced by conditions (temperature gradients, cooling rates external magnetic fields). Another finding that when rotating upwards directional solidification, under transverse field 0.5T, highly refined well aligned obtained, much finer than those without imposition field. attributed rotational stirring flow modulates regulates temperature solute distribution. developed experimental findings provide physical understanding formation solidification.