Mechanical Properties of Metallic Films on Sapphire

ABSTRACTA knowledge of interfacial mechanical properties is of considerable importance to the areas of oxidation, corrosion, metallization, and composite materials. We have developed an experimental apparatus capable of simultaneous measurements of elastic and anelastic properties of materials in controlled atmospheres (10-6 to 104 Pa) from 25 to 1000°C. The apparatus employs the technique of dynamic reasonance in which a material's mechanical resonance spectrum can be determined over a range 102 to 105 Hz with resolution ±0.001 Hz. This resolution has enabled us to determine the mechanical properties of films as thin as approximately 10 nm.We shall present resonance results for thin films (∼100 nm) of nickel and gold on sapphire substrates. These results suggest that nickel films on sapphire are adherent, i.e., cyclic strain is continuous at the film-substrate interface, over a range of temperature about the film growth temperature; whereas gold films show nonadherent behavior at all temperatures studied.