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Curriculum and courses' programs
Defects in crystals
B.B. Straumal
Lectures program for the undergraduate students of the Faculty of general and applied physics of Moscow Institute of Physics and Technology (State University)
The defect-free and unlimited solid is though a useful ideal construction, but it is quite far from reality. Indeed, the properties of condensed state are often fully controlled by the crystalline defects. In these lectures the defects are classified according those dimensionality. At the beginning, the 0-dimensional defects like vacancies, interstitials, dislocation kinks and kinks of surface steps are discussed. Then we discuss the linear 1-dimensional defects like dislocations and triple junctions of interfaces. Later follow the 2-dimensional defects like free surfaces and crystal interfaces. The amorphous state or quasicrystals without long-range translational order can be treated as 3-dimensional defects. We discuss in these lectures not only the structure of defects, but also their properties, interactions, how they appear and disappear, as well as the phase transformations with their participation.
Lecture 1. Point defectsVacancies. Interstitials. Their formation and migration. Frenkel and Schottky defects. Reactions between point defects, their electronic properties.
Lecture 2. Point defects
Combinations of atomic defects. Transition from point defects to 1-dimensional, 2-dimensional, and 3-dimensional ones. Stacking fault tetrahedra. Pores. Pore coalescence, their role in sintering.
Lecture 3. Linear defects
Dislocations. Edge, screw and combined dislocations. Burgers vector. Dislocation energy. Glide and climb of dislocations. Interaction between dislocations. Interaction between dislocations and impurities. Plastic deformation as a result of dislocation movement.
Lecture 4. Linear defects
Dislocation sources. Dislocation mobility. Mechanisms of dislocation movement. Geometrical charactetistics of dislocations. Elastic fields of dislocations. Disclinations. Atomic structure of dislocation cores.
Lecture 5. Linear defects
Partial dislocations and stacking faults. Experimental methods of investigation of dislocations. Deformation of single crystals and polycrystals. Influence of grain boundaries on the plastic deformation of polycrystals.
Lecture 6. Linear defects
Low-angle grain boundaries. Walls and networks of lattice dislocations. Influence of dislocations on the physical (electrical, optical, thermal) properties of solids. Transition from 1-dimensional defects to 2-dimensional, and 3-dimensional ones.
Lecture 7. Two-dimensional defects. Surfaces.
Faceting-roughening transition of solids surfaces with increasing temperature. Wulff diagrams. Faceting-roughening transition and Peierls barrier in metals, semiconductors and dielectrics.
Lecture 7. Two-dimensional defects. Surfaces.
Rips of first and second order between faceted and rough surfaces. Andreev and Pokrovsky-Talapov models. Critical points on the 2-dimensional phase diagrams. First order rips between two rough surfaces.
Lecture 8. Two-dimensional defects. Surfaces.
Reconstruction of pure surfaces. Single- and multilayer adsorption of free surfaces. Formation of 2-dimensional phases in adsorbed layers. Complete, incomplete, pseudoincomplete wetting of free surfaces. Transitions from incomplete to complete wetting with increasing temperature. Dependence between complete wetting and multilayer adsorption. Methods of experimental investigation of free surfaces.
Lecture 9. Two-dimensional defects. Interfaces.
Interpenetrating crystal lattices. Coincidence site lattice, displacement-shift lattice, grain boundary displacements lattice, 0-lattice. Coincidence and near-coincidence site lattices. Low-angle and high-angle grain boundaries. Walls and networks of lattice dislocations.
Lecture 10. Two-dimensional defects. Interfaces.
Merging of lattice dislocations cores. Grain boundary dislocations. Intrinsic and extrinsic grain boundary dislocations. Burgers vector of grain boundary dislocations. Climb and glide of grain boundary dislocations. Epitaxy and misfit dislocations in interphase boundaries. Dissociation of lattice dislocations into grain boundary ones. Equlibrium and non-equlibrium grain boundaries.
Lecture 11. Two-dimensional defects. Interfaces.
Faceting-roughening transition of grain boundaries with increasing temperature. Difference from free surfaces. Wulff diagrams. Andreev and Pokrovsky-Talapov models. 'Special-general' grain boundary phase transitions, their connection with the faceting-roughening transitions. The difference between grain boundary phase transitions in ideal and not-ideal lattices. Transition of first-order facet-to-rough grain boundary rips into rough-to-rough rips.
Lecture 12. Two-dimensional defects. Interfaces.
Interfaces in two- and multicomponent systems. Single- and multilayer adsorption in interphase and grain boundaries. Complete, incomplete, pseudoincomplete wetting of interfaces. Transitions from incomplete to complete wetting with increasing temperature. Dependence between complete wetting and multilayer adsorption. Wetting by a second solid phase, difference from the wetting by a liquid phase. Thin layers of grain boundary phase in solid solutions. Wetting phase transformations of first and second order. Transition from 2-dimensional defects to 3-dimensional ones.
Literature
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- Б.Б. Страумал, Фазовые переходы на границах зерен, М., Наука , 2003, 328 с.
- Р.З. Валиев, И.В. Александров. Наноструктурные материалы, полученные интенсивной пластичексой деформацией. М., Логос, 2000, 272 с.
- И.И. Новиков. Дефекты кристаллического строения металлов. М. Металлургия, 1975, 208 с.
- В.С. Золоторевский, Механические свойства металлов. М. Металлургия, 1983, 352 с.
- Б.С. Бокштейн. Диффузия в металлах. М. Металлургия, 1978, 252 с.
