The growth stress of Ti50CU50 alloy films on alumina substrates was measured in situ under ultrahigh vacuum conditions with a cantilever beam technique as a function of substrate temperature and variation of copper concentration. The growth stress of films deposited at low temperature is interpreted to indicate the growth of amorphous respectively nanocrystalline films. At substrate temperatures above 300 degreesC, a novel tensile stress contribution is interpreted to be due to the formation of a preferentially oriented film of metastable copper vacancy superstructured gamma-TiCu. Finally, at substrate temperatures above 365 degreesC, a polycrystalline gamma-TiCu film is formed. Annealing of low-temperature alloy films gives rise to irreversible tensile stress changes indicating restructuring of the films. The stress change measured when annealing a superstructured gamma-TiCu film is compressive and is assigned to the transformation of the metastable superstructure to polycrystalline gamma-TiCu. The magnitude of this compressive stress contribution is strongly dependent on the copper concentration, i.e., copper vacancy concentration. (C) 2004 Elsevier B.V. All rights reserved.