Metallographic sample preparation techniques

Microstructure plays an important role in controlling the properties in metals and alloys. Hence Microstructural studsy called metallography has been extensively used for materials selection, failure investigation and materials development. The microstructure of metals are commonly observed under optical and/or electron microscopes, though other types of microscopes have been developed for specific uses. For any microscopic observation, the preparation of proper sample, which reveals the true microstructure is of primarv importance. Numerous and diverse techniques have been developed not only to suit the ma¬terial but also for the type of microscope to he used. The techniques also vary with the details to be observed. It is difficult to prepare a comprehensive survey of the techniques developed and practised to¬day. An attempt has been suede here, to briefly discuss the most com¬monly used specimen preparation techniques for optical, scanning electron and transmission electron microscopy together with their merits and demerits. Any specimen preparation method involves several steps. Proper care in each step is essential to avoid difficulty in the subse¬quent steps and to reveal the true microstructure. The choice of a technique depends mainly on the materials, the detail required to be observed and the type of microscope to be used.