STABILITY AND ELASTIC PROPERTIES OF AMORPHOUS AL-ZR-O FILMS

Amorphous, 200 nm thin multilayer structures (including films composed of the pure constituents) and homogeneously mixed films, respectively , were prepared by alternating deposition and co-deposition of alumina and zirconia. Subsequent heating of the films showed crystallization temperatures between 850 and 950-degrees-C. At 1000-degrees-C, the sel ective crystallization of metastable cubic zirconia was observed. The elastoplastic properties of the amorphous films were examined using ul tra-low load indentation tests. The hardness and the Young's modulus o f multilayer structures varied linearly with the overall alumina-zirco nia composition. Homogeneously mixed films, by contrast, deviated from such a linear relationship. They exhibited a hardness higher than eve n alumina films and simultaneously a Young's modulus lower than even z irconia films over a wide concentration range. Different proportionali ties between hardness and Young's modulus were observed for the multil ayer and the homogeneous films. These results indicate that the molecu lar mixing of the constituents led to an increase of both the yield st rength and the maximum elastic tensile strain.