Tensile properties of aluminum/alumina multi-layered thin films

Thin, free standing aluminum and alumina films were produced by physical vapor deposition and tensile properties were measured. Young’s modulus of the aluminum was microstructure insensitive, but the plastic behavior was very structure sensitive. The natural surface oxide of the aluminum had no apparent affect on the measured value ofYoung’s modulus. The alumina films showed true brittle behavior, but Young’s modulus was lower than bulk. Impurities residing at the grain boundaries were observed in the aluminum films using transverse Auger electron spectroscopy (AES). The films were well characterized using AES, transmission electron microscopy, Rutherford backscattering spectroscopy, and secondary electron microscopy. Well characterized, thin three-layered aluminum/alumina compositionally modulated films were produced by alternate depositions and tensile properties were measured. Young’s modulus was found to be less than a weighted thickness average of Young’s modulus of the individual constituents. Otherwise, the mechanical measurements yielded typical bulk behavior.