Structure Refinement and Fragmentation of Precipitates under Severe Plastic Deformation: A Review

During severe plastic deformation (SPD), the processes of lattice defect formation as well as their relaxation (annihilation) compete with each other. As a result, a dynamic equilibrium is established, and a steady state is reached after a certain strain value. Simultaneously, other kinetic processes act in opposite directions and also compete with each other during SPD, such as grain refinement/growth, mechanical strengthening/softening, formation/decomposition of solid solution, etc. These competing processes also lead to dynamic equilibrium and result in a steady state (saturation), albeit after different strains. Among these steady-state phenomena, particle fragmentation during the second phase of SPD has received little attention. Available data indicate that precipitate fragmentation slows down with increasing strain, though saturation is achieved at higher strains than in the case of hardness or grain size. Moreover, one can consider the SPD-driven nanocrystallization in the amorphous phase as a process that is opposite to the fragmentation of precipitates. The size of these crystalline nanoprecipitates also saturates after a certain strain. The fragmentation of precipitates during SPD is the topic of this review.

FINANCIAL SECURITY OF THE REGION: SCIENTIFIC APPROACHES TO THE IDENTIFICATION OF THE CONCEPT

Ensuring financial security at all levels of government is an important task for many countries, including Ukraine. It is impossible to solve the economic problems facing the country, region and enterprise without providing them with financial security. This task is becoming a particular priority in the face of instability and financial crisis. The purpose of the article is to generalize the theoretical provisions on the essence of financial security of the regions, to identify its main components and areas of support. The article presents the interpretation of the concept of the region in the framework of different approaches of scientists. The most important blocks of the structure of economic security of the region are revealed: financial independence, stability and stability of the regional economy, ability to self-development and progress. The main approaches to the essence of the concept of “financial security” are systematized, the essence of the concept of “financial security system of the region” is considered. The principles of economic security of the region are given: general, namely: complexity, system, variability (alternatives), the principle of coordination (coordination) of relations and relations of all elements of economic security of the region, the principle of specialization elements (separation of functions and operations performed by elements). Based on the obtained results, the directions of strengthening the financial security of the region are proposed. In the current conditions of economic development of Ukraine, first of all it is necessary to move in the direction of improving the system of financial security, namely: establishing the boundaries of foreign participation in the capital of domestic organizations; introduce industry restrictions; development of effective control systems for attracting and using foreign borrowings. We believe that the country’s financial security system should ensure the solution of the following tasks: creating a full-fledged national currency and maintaining it in a stable and competitive state; saturation of the economy and the market with money supply in the amount necessary for their full functioning and development; creation of conditions provide intensive formation of competitive national financial capital denominated in national currency; ensuring financial parity with Ukraine’s main competitors in the medium term.