Unveiling the Growth Mechanism of Faceted Primary Al2Cu with Complex Morphologies During Solidification

The growth characteristic of primary faceted Al2Cu intermetallic compounds (IMCs) during solidification was observed directly by synchrotron radiography. The formation and transition mechanisms of Al2Cu IMCs with diverse morphologies were elucidated by first-principle calculations combined with electron backscatter diffraction analysis. The Al2Cu crystals preferred to grow along the [001] direction and were bounded by {110} planes with the lowest surface energy. The faceted Al2Cu rod-like clusters consisted of multiple crystals with complete rod, hollowness and partial sides, which was attributed to the increase in strain energy and solute redistribution during solidification. The faceted Al2Cu with branches was characteristic with the perpendicular relationship between the main branches and side steps and partial coalescence at the junction, which was ascribed to the continuous propagation and growth of newly formed crystals along the diagonal direction.

Automated summary

The growth characteristics and morphological development of Al2Cu intermetallic compounds during solidification were studied using synchrotron radiography and first-principle calculations, revealing the preferential growth direction of Al2Cu crystals and the mechanisms behind their formation and transition. The faceted Al2Cu clusters were found to exhibit unique features such as branch formations and partial coalescence, attributed to strain energy increase and solute redistribution during solidification.