Інтенсивна пластична деформація: методи та математичні моделі формування наноматеріалів

Abstract

The paper explores methods of obtaining ultrafine-grained and nanostructural materials and corresponding theoretical models. The focus is on the methods of severe plastic deformation: examples of schemes and features of the treatment process are given. Experimental studies of obtaining nanocrystalline structures in various metals or alloys in the process of severe plastic deformation are described. These studies can be used for the synthesis of metals of different classes for the manufacture of constructions for a suitable purpose. In particular, the reasons for the formation of unstable configurations or manifestations of abnormal effects in the material properties, which are common in practice and can lead to premature destruction during operation, have been identified. Theoretical approaches to the description of the process of solids fragmentation during severe plastic deformation are reviewed. The method of nonequilibrium evolution thermodynamics is considered, which makes it possible to unambiguously establish the behavior of nonequilibrium variables during the processing of solids. The phenomenological foundations of the approach that unite the first and the second laws of thermodynamics are presented, and a model is proposed that allows describing the specifics of the process of the fragmentation and formation of a limiting (stationary) structure during the severe plastic deformation. Taking into account the two-defect approximation, the main relationships are determined in terms of effective internal energy, and the stages of the fragmentation process are described. The study shows that the Taylor relation provides a self-consistent feedback between the process of the formation of a stationary structure and the condition of its formation in the form of acting stresses. The conclusion is that there are a number of questions regarding severe plastic deformation that have not yet been fully investigated. It is these questions that should be in the main focus of future studies.Розглянуто методи отримання та відповідні теоретичні моделі ультрадрібнистих та наноструктурних матеріалів. Основну увагу приділено методам інтенсивної пластичної деформації.