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 Cu ₂ O/Cu(OH) ₂ surface layer within 24 h. Subsequent post‐treatment heating promotes the transformation CuO CuO, in accordance with established low‐temperature oxidation pathways. Casting under XHV‐equivalent conditions yields fully bonded Al–Cu interfaces with the expected Al ₂ Cu, AlCu, and Al ₄ Cu ₉ 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.