Phasentransformation unter extremen Nicht-Gleichgewichtsbedingungen

A common feature of novel technologies for the production of materials for advanced structural and functional applications is that phase formation frequently occurs under extremely non-equilibrium conditions. In particular this applies to materials produced by high-energy ball milling of powder blends, atomisation of the melt, condensation techniques and ion irradiation of alloys, but also to laser processing and several other cutting and surface modification methods. Due to the high driving forces of phase reactions, new phase selection phenomena are observed, which are less determined by the thermodynamics of the system but more by the atomic mobilities in the competing phases. Striking examples are the formation of metastable and even unstable phases, the (inverse) melting of supersaturated solid solutions upon cooling and the occurrence of a kinetically controlled phase selection during interface reactions. This new area of materials science will be highlighted by selected examples. First approaches to obtain a quantitative description of phase reactions under highly non-equilibrium conditions will be outlined, which unify thermodynamic and kinetic descriptions. (orig.)Reprinted from: F.Aldinger; H.Moghrabi (eds.): Werkstoffwoche '96 -Symposium 7, DGM-Verlagsgesellschaft, 1997, p. 87-94Available from TIB Hannover: RA 3251(97/E/16) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman