Regensburg 2002 – wissenschaftliches Programm
PV XI: Plenarvortrag
Freitag, 15. März 2002, 08:30–09:15, H1
Theoretical Characterization of Alloy Structures at Mesoscopic Scales — •Armen G. Khachaturyan, Y. U. Wang, and Y. Jin — Ceramic and Materials Engineering, Rutgers University
Diffusional transformations (decomposition and ordering) and diffusionless transformations (martensitic and ferroelastic) produce nanoscale/mesoscale systems that consist of structural or compositional domains of the product phase with different atomic structures and/or compositions. A crystal lattice misfit at interfaces of the domains generates the elastic strain resulting in the dipole-dipole like long-range interaction between the domains, which is mathematically similar to the corresponding interaction between ferroelectric and ferromagnetic domains. This strain-induced interaction is responsible for an energy-minimizing domain structure similar to the domain structures in ferroelectric/ferromagnetic systems. These microstructures produced by phase transformations are a subject of intensive studies because the physical properties of a material are strongly dependent on the nanoscale and mesoscale microstructure geometry. Domains produced by the phase transformation are strain-generating crystal lattice defects. The specifics of their interaction with other defects such as dislocations and cracks and the dependence of this interaction on the domain microstructure determine the structure-property relations. The recent advances in the theory of phase transformation and micromechanics of structurally inhomogeneous systems and, in particular, the Phase Field Microelasticity theory of the phase transformation-induced domain structure, dislocations, cracks, and voids are discussed. The Phase Field Microelasticity theory opens a way to a realistic 3D computational modeling of the domain microstructure of an arbitrary complexity and establishing the relation of this microstructure to properties of major technologically important materials such as intermetallic alloys and shape memory martensitic alloys. Examples of 3D simulations of the microstructure evolution in intermetallic alloys and martensitic shape memory alloys, as well as a simulation of the evolution of multi-dislocation and multi-crack systems in single- and polycrystals during the deformation process are presented.