Ageing effects in bimetallic films

Publisher Website
Google Scholar
Abstract
Measurements of adhesion have been made on films of silver, gold, copper and aluminium with under layers of chromium. The films have all been deposited on glass microscope slides by vacuum evaporation and the adhesion has been measured by drawing a smoothly rounded point across the surface whilst increasing the load on the point until a clear, well-defined channel was produced. It has been shown that in the case of bimetallic films, abnormally high figures may be obtained due to the formation of an intermediate layer by diffusion or intermetallic reaction. The results show a dependence upon the thickness of the chromium underlayer and time as well as upon the metal of the upper layer. Explanations are based upon a structural model for chromium films which assumes an aggregated structure formed of oxide-coated particles below 400 Å thickness and a continuous metallic structure above this thickness. It is shown that intermediate layer formation occurs only when the thickness of chromium exceeds 400 Å and where some degree of miscibility of the two metals exists. The rate of ageing depends upon the extent of miscibility.

This publication has 7 references indexed in Scilit: