Recently, the authors have shown that single-phase Al2Au coatings, prepared by unbalanced macynetron sputtering, exhibit a dense columnar structure and highest hardness and indentation moduli of 8 and 144 GPa, respectively, within the Al-Au films investigated. This study focuses on the thermal stability of Al2Au with respect to films containing more Al and An having Al/Au at. % ratios of 4.32 and 1.85, respectively. Single-phase Al2Au has the highest onset temperature for recovery of 475 degrees C and recrystallization of 575 degrees C. Upon annealing Au- and Al-rich films, their stresses deviate from the linear thermoelastic behavior at temperatures (T) above 200 and 450 degrees C, respectively, due to pores and metallic phases present. Metastable An within the as-deposited Au-rich film is consumed by the growing intermetallic AlAu and AlAu2 phases at T >= 450 degrees C, which themselves melt at similar to 625 degrees C. Due to nanometer scale segregations of Al, encapsulated by Al2Au in Al-rich coatings, their melting point is reduced by similar to 85 degrees C to 575 'C. Dynamic thermal analyses up to 1100 'C in synthetic air reveal the single-phase Al2Au films with a superior thermal stability and only negligible oxidation. At 750 degrees C, the mass gain is similar to 1.5 mg/cm(2) after 50 h isothermal exposure. Based on the investigations, the authors can conclude that single-phase intermetallic Al2Au films have a high potential for oxidation protection of sensitive materials. (c) 2007 American Vacuum Society.