LANDSCAPE ROUGHNESS AT AN ATOMIC-SCALE

A large number of materials have a highly degenerate ground state and therefore a complex microstructure. Because of this degenerate state, phase transitions between the different phases play an important role. High resolution techniques in electron microscopy and nano-scale chem ical analysis allow to study not only the microstructure but also the interfaces down to an atomic scale. We focus particularly on the ambig uity of alloys oil approaching the phase transition. The short range o rder (SRO) in ''1 1/20'' type alloys and the microstructure of ''tweed '' and needle formation in martensite like alloys with composition Ni5 Al3 are considered in more detail.