Insights into the Formation of Al–Cu Intermetallic Compounds During the Solid–Liquid Reaction by High-Resolution Transmission Electron Microscopy

During Al/Cu solid–liquid reaction, different intermetallic compounds (IMCs) are expected, which can affect the mechanical and electrical properties of Al/Cu joints. To tackle this challenge, it is then necessary to tune the interface structure, which requires an insight into the formation mechanism of IMCs. In the current study, Al/Cu liquid–solid reaction was used to fabricate different IMCs. With the aid of a focused ion beam (FIB) and high-resolution transmission electron microscopy (HRTEM), the distribution of IMCs along the Al/Cu interface was determined. Meanwhile, the orientation relationship among different IMCs and Cu with coherent structure was identified. This study provides a fundamental understanding of the mechanism behind the Al/Cu reaction, which may guide the performance improvement of Al/Cu dissimilar weld.