Metallographic Specimen Preparation

/.letallography is much more than taking striking pictures at high magnifications or polishing and etching specimens in such a way that no scratches can be seen. Basically, metallography is the physical metallurgist's most useful and most used tool for studying metals. Although it is perhaps his oldest tool, it certainly is not likely to become obsolete. Rather, the continued demands that have been placed upon materials have required more detailed charac- terizations of their microstructures and this, in turn, has re- quired the metallographer to develop new techniques to make these characterizations. Not too many years ago, the metallographer had only optical microscopes with which to examine his specimens. Now he has elec- tron microscopes, scanning electron microscopes, and a whole host of instruments which were unknown to him only a relatively few years ago. This has forced him to learn not only how to use these new instruments and how to interpret the information that they provide but it also has made him develop new techniques for preparing the samples for examination.