In Situ Investigation of Microstructural Evolution and Intermetallic Compounds Formation at Liquid Al/Solid Cu Interface by Synchrotron X-ray Radiography

Abstract

Synchrotron radiation dynamic imaging technology combined with the static characterization method was used to study the microstructural evolution and the growth kinetics of intermetallic compounds (IMCs) at the liquid Al/solid Cu interface. The results show that the interfacial microstructure can be divided into layered solid diffusion microstructures (AlCu₃, Al₄Cu₉, Al₂Cu₃ and AlCu) and solidification microstructures (Al₃Cu₄, AlCu and Al₂Cu) from the Cu side to the Al side. Meanwhile, the growth of bubbles formed during the melting, holding and solidification of an Al/Cu sample was also discussed, which can be divided into three modes: diffusion, coalescence and engulfment. Moreover, the growth of AlCu₃ and (Al₄Cu₉ + Al₂Cu₃) near the Cu side is all controlled by both interfacial reaction and volume diffusion. The growth of Al₃Cu₄ adjacent to the melt is mainly controlled by the interfacial reaction, which plays a major role in the growth of the total IMCs.

Keywords: bubble growth; intermetallic compounds; liquid Al/solid Cu interface; microstructure; synchrotron X-ray radiography.