LASER-ABLATION DEPOSITION OF CU-NI AND AG-NI FILMS - NONCONSERVATION OF ALLOY COMPOSITION AND FILM MICROSTRUCTURE

Laser ablation deposition was used to grow polycrystalline Cu-Ni and A g-Ni thin films on amorphous substrates at room temperature. X-ray dif fraction was employed to determine the phases present and the residual macrostress and to analyze the structural imperfection in terms of cr ystallite size and microstrain. For confirmation and complementary mic rostructural data transmission electron microscopy was applied. Analys is of the gross composition was achieved by electron probe microanalys is and x-ray fluorescence. The films contained substantially less Cu a nd Ag than the targets, which was caused by preferential scattering of ablated Cu and Ag species upon incidence at the growing films. The Cu -Ni films were entirely composed of a CuxNi1-x solid solution. The Ag- Ni films were composed of a AgxNi1-x solid solution and of pure Ag and pure Ni. The nonequilibrium AgxNi1-x solid solution could contain up to 44 at. % Ag. The residual macrostress in the Cu-Ni films was compre ssive, whereas it was tensile in the Ag-Ni films. The occurrence of th ese stresses could be interpreted as due to the combined effects of at omic peening and cooling after deposition and, in the case of the Ag-N i films, of stress relaxation by partial decomposition of the AgxNi1-x solid solution during film growth. The microstrains in the AgxNi1-x s olid solutions were higher than in similarly prepared pure elemental A g and Ni films. Compositional inhomogeneity of the AgxNi1-x solid solu tion crystallites contributed in particular to this effect. The strain -free lattice parameters of the solid solutions were found to be in fa ir agreement with those predicted by Vegard's law.