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Nanoscience and Technology: An International Journal

ISSN Print: 2572-4258
ISSN Online: 2572-4266

Nanoscience and Technology: An International Journal

Formerly Known as Nanomechanics Science and Technology: An International Journal

DOI: 10.1615/NanomechanicsSciTechnolIntJ.v7.i1.10
pages 1-25

THERMODYNAMICS WITH ADDITIONAL PARAMETERS FOR POLYCRYSTALS

Anna G. Knyazeva
Institute of Computational Technologies, SB RAS Tomsk Polytechnic University, Tomsk, Russian Federation

ABSTRACT

Multiphase and multicomponent polycrystals have the features typical of homogeneous and heterogeneous media. Various structural regularities in solids and evolution of their structure under the conditions of treatment, synthesis, and exploitation of materials lead to the necessity to modify or to clarify the classical models of the behavior of such media. The extension of the model of a multicomponent solid body by adding such variables as the vacancy concentration and specific area of internal surfaces to the parameters allows describing nontraditional cross phenomena in polycrystalline materials and indicating new transfer mechanisms related to the mutual effects of the fields of different physical nature. For nanostructured materials, internal interfaces become the main factor that allows detecting specific properties. The internal surfaces by some of their properties are close to active external surfaces which begin to play a special role when the sizes of the thermodynamic system decrease. The work uses traditional approaches of the thermodynamics of irreversible processes and describes possible ways of the effect of internal surfaces on the processes of different nature, viz., on changes in temperature under the conditions of constant stress and strain and under conditions of phase transitions. Different forms of nonequilibrium equations of state are presented; the components of full deformation tensor connected with various physical phenomena are identified. The concepts of generalized coefficients of diffusion are introduced under the effects of internal interfaces. Various variants of Maxwell thermodynamic equations are given for media with vacancies and internal surfaces. It is demonstrated that a number of independent coefficients can be reduced by taking into account the cross effects and the symmetry of thermodynamic relations.