Abstract
Possibilities of using laser irradiation to enhance mass transfer in the solid phase of metallic materials in order to form structures with improved physical and mechanical properties were reviewed. The features of the diffusion mass transfer in metals and alloys under shock exposure were specified. In this case, the rate of diffusion processes of mass transfer can be significantly increased. The conditions for intensification of mass transfer in metallic materials by pulse-periodic laser irradiation were determined and the synthesis of nanoporous and composite oxide nanomaterials was described. A significant increase of the diffusion coefficient in a metallic material, in comparison to plain exposure to laser beam heating, was identified. It could be attributed to the synergy of heat exposure and laser-induced vibrations, mainly in the range of sound frequencies, as a result of a pulse-periodic laser irradiation. The condition for intensifying mass transfer in the solid phase of selectively oxidable metallic materials was identified as a non-stationary stress-strain state caused by laser-induced sound waves. The exploitation of this synergy effect permitted the implementation of a novel approach for the creation of structures of nanomaterials. At the same time, a targeted influence on mass transfer and the accompanying relaxation processes make it possible to achieve an increase in the efficiency of methods for processing metals and alloys.
Highlights
The creation of new technological methods of exposure, which ensure the formation of structures of materials with the required properties [1,2,3], is one of the possibilities that can solve the task of increasing the operational characteristics of mechanical engineering products
It could be attributed to the synergy of heat exposure and laser-induced vibrations, mainly in the range of sound frequencies, as a result of a pulse-periodic laser irradiation
The exploitation of this synergy effect permitted the implementation of a novel approach for the creation of structures of nanomaterials
Summary
The creation of new technological methods of exposure, which ensure the formation of structures of materials with the required properties [1,2,3], is one of the possibilities that can solve the task of increasing the operational characteristics of mechanical engineering products. In addition to changes in the grain size and microstructure of metals and alloys, diffusion processes cause the appearance of nanostructural effects: a change in the angular misorientations of subgrains in the grain composition, crushing of blocks, the formation of an ordered distribution of nanosized inclusions and pores, a change in the level of microdistortions, and dislocation density. These effects have the potential to improve such structure-dependent properties as mechanical strength, hardness, and plasticity, and electrical conductivity, thermal conductivity, optical characteristics, etc. Increasing the temperature is an effective way to increase the mobility of atoms, since the diffusion coefficient is exponentially related to temperature, but in some cases this method has significant limitations, for example, due to grain growth and material embrittlement [6,7].
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