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 significance in the protection and degradation of such materials under service conditions. The understanding of film morphology, composition and structure and their relation to the transport processes responsible for film growth, is essential in developing protection strategies. High resolution analytical transmission electron microscopy of sections of the films attached to the metal-alloy substrate provides a route towards the required understanding. Here, examples of various amorphous and crystalline films, together with films revealing amorphous to crystalline and crystalline to amorphous transformations during growth, are emphasized. Such situations illustrate the need for examination over a wide 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 applicable to both fundamental and practical situations with an easily understood technology transfer between them.