Al2Cu thin films (similar to 382 nm) are fabricated by melting and resolidifying Al/Cu bilayers on a SiO2 on Si(100) substrate in the presence of a similar to3 nm Al2O3 passivating layer. X-ray photoelectron spectroscopy (XPS) measures a 1.0 eV shift of the Cu 2p(3/2) peak and a 1.6 eV shift of the valance band relative to metallic Cu upon Al2Cu formation. Scanning electron microscopy and electron back-scattered diffraction show that the Al2Cu film is composed of 30-70 mum wide and 10-15 mm long cellular grains with (110) orientation. The atomic composition of the film as estimated by energy dispersive spectroscopy is 67 +/- 2% Al and 33 +/- 2% Cu. XPS scans of Al2O3/Al2Cu taken before and after air exposure indicate that the upper Al2Cu layers undergo further oxidation to Al2O3 even in the presence of similar to5 nm Al2O3. The majority of Cu produced from oxidation is believed to be excluded from the Al2O3 layers, based upon the lack of evidence for metallic Cu in the XPS scans. In contrast to Al/Cu passivated with Al2O3. melting/resolidifying the Al/Cu bilayer without Al2O3 results in phase-segregated dendritic film growth.