THE SCOPE FOR STUDIES OF THIN SURFACE-FILMS ON METALS AND ALLOYS BY TRANSMISSION ELECTRON-MICROSCOPY OF ULTRAMICROTOMED SECTIONS

Thin surface films on metals and alloys have immense practical signifi cance in the protection and degradation of such materials under servic e conditions. The understanding of film morphology, composition and st ructure and their relation to the transport processes responsible for film growth, is essential in developing protection strategies. High re solution analytical transmission electron microscopy of sections of th e films attached to the metal-alloy substrate provides a route towards the required understanding. Here, examples of various amorphous and c rystalline films, together with films revealing amorphous to crystalli ne and crystalline to amorphous transformations during growth, are emp hasized. Such situations illustrate the need for examination over a wi de resolution range, defining with precision the general behaviour and specific local properties of crucial importance to corrosion science. Further, the direct observation approach is highly flexible, being ap plicable to both fundamental and practical situations with an easily u nderstood technology transfer between them.