Al–Cu Composite Casting of Laser-Deoxidized Copper: Bonding, Interfacial Chemistry, and Thermal Conductivity

This work addresses a central challenge in Al–Cu compound casting: native copper oxides, which inhibit wetting and metallurgical bonding. A laser-based deoxidation strategy (ns-pulsed, 1064 nm) performed under oxygen-free, XHV-equivalent glovebox conditions, and quantifying subsequent oxide regrowth during realistic short-term handling, is demonstrated. Surface roughness was tuned via pulse/line overlap (0% vs. 70%) and characterized using confocal microscopy and power spectral density analysis. X-ray photoelectron spectroscopy reveals that laser processing under XHV-equivalent conditions produces copper surfaces that are more than 98% oxide-free and remain predominantly metallic for at least 720 h, whereas exposure to ambient air rapidly leads to the formation of a Cu₂O/Cu(OH)₂ surface layer within 24 h. Subsequent post-treatment heating promotes the transformation Cu (Formula presented.) O (Formula presented.) CuO, in accordance with established low-temperature oxidation pathways. Casting under XHV-equivalent conditions yields fully bonded Al–Cu interfaces with the expected Al₂Cu, AlCu, and Al₄Cu₉ intermetallic layers. Intermetallic compound (IMC) morphology is more strongly governed by processing parameters (temperature, expected melt-to-solid ratio, and thermal history) than by minor short-term oxide regrowth. Overall, laser deoxidation under XHV-equivalent conditions emerges as a pretreatment that improves wetting, enables controllable IMC formation, and preserves high interfacial thermal conductivity in Al–Cu composite castings.