FRACTAL MICROSTRUCTURES OF METALS

Fractal analysis deals with disordered microstructures, i.e. rough and rugged surfaces or folded lines. Their quantitative description is di fficult with conventional methods. They can be characterized by the no n-integer fractal dimension D > d. Fractal analysis is applied on micr ostructural elements which are usually described by the Euclidian dime nsion 0 less-than-or-equal-to d less-than-or-equal-to 3, i.e. vacancie s, dislocations, grain boundaries or dispersoid particles. Prerequisit e is the self-similarity of the structure. This means that a similar m orphology appears in a wide range of magnification. Examples are given for.fractal analysis of dislocations, grain boundaries, particle dist ribution and surfaces. Finally, reference is made to the application o f fractal analysis on fractured and sliding surfaces in tribological s ystems. A microstructural analysis with fractal analysis is given for lenticular martensite of a Fe-Ni alloy. It implies the amount of forme d martensite as well as the size spectrum of martensite crystals and d istribution of retained austenite. In addition, the length of the mart ensite/austenite interface and the interface density were determined.