Structure of sputter-deposited films of β-tantalum-aluminum alloys

Ion-plasma sputtering and the codeposition of ultradisperse particles of Ta and Al have been used to prepare solid solutions in the entire range of concentrations of the binary system in the form of alloy coatings. The formation of the solid solution of these alloys directly in the process of codeposition confirms the theory of the thermofluctuation melting of small particles and coalescence of quasi-liquid clusters of subcritical size. Upon the formation of coatings via the deposition of nanolayers of tantalum of less than 0.8 nm for β-Ta and 1.1 nm for Al, the spontaneous mutual dissolution of the components occurs with the formation of solid solutions of one metal in the other. Beginning with a concentration of ～85 at % Al in the alloy, Al atoms control the type of symmetry of the arising lattice. An increase in the characteristic dimensions (thickness of sublayers) of tantalum and aluminum leads to the appearance of solid solutions of these metals in these coatings in addition to the β tantalum and aluminum phases, as well as of amorphous regions and superlattices formed by nanoclusters of one metal in the matrix of the other. It has been established that the formation of these superlattices is controlled by the size factor.