@article{Poyda_Milaya_Poyda_Bryukhovetskiy_Petrushenko_Dukarov_2020, title={Mechanisms of cavity formation and development during superplastic deformation of high-strength aluminum alloy 1933 with bimodal grain structure}, url={https://periodicals.karazin.ua/physics/article/view/16126}, DOI={10.26565/2222-5617-2020-32-02}, abstractNote={<p>The mechanisms of cavity formation and growth during high-temperature superplastic deformation of high-strength aluminum<br>alloy 1933 with bimodal grain structure are considered. Superplastic deformation of the samples was performed at a temperature<br>Т = 520С, flow stress σ = 5,5 MPa, true strain rate  = 1,2∙10-4 s-1. Samples of alloy 1933, superplastically deformed under such<br>conditions, by the time of fracture, accumulate deformation, the relative degree of which is 230%. It is shown that, in superplastically<br>deformed samples of alloy 1933, grain-boundary cavities originate due to the formation of wedge-shaped cracks at high-angle and lowangle<br>grain boundaries perpendicular to the fracture direction of samples, as well as due to the appearance of thin elongated microcracks&nbsp;at low-angle grain boundaries parallel to tension direction. It is revealed that cavities form and grow mainly due to the development of<br>grain boundary sliding. It takes place both at high-angle and low-angle grain boundaries, which are solid, or contain areas of viscous<br>liquid phase, which was formed as a result of partial melting of an alloy heated to a high homologous temperature. During the shape<br>changing and growth of grain-boundary cavities at the solid grain boundaries and at the boundaries of those grains that contain local<br>foci of the liquid phase formed as a result of partial melting of the 1933 alloy upon heating of its samples to the test temperature, fibrous<br>structures arise and grow due to the viscous flow of foci of the liquid phase. It has been revealed that all fibrous structures that were<br>formed in samples of the 1933 alloy during superplastic deformation can be conditionally divided into three types: type 1 – thin<br>cylindrical fibers; 2nd type – cone-shaped fibers; type 3 – fibers that have a ribbon-like view. It is shown that the localization of plastic<br>flow in ultrafine and coarse grains, of which the bridges between discontinuities in the microvolume of the sample, from which is<br>consist the most weakened due to the accumulation of cavities, lead to their failure. As a result, grain-boundary cavities and thin<br>elongated microcracks combine into a main crack, the development of which in the working part of the 1933 alloy sample in the<br>direction perpendicular to the tension direction leads to its destruction.</p> <p>&nbsp;</p>}, number={32}, journal={Journal of V.N. Karazin Kharkiv National University, series "Physics&quot;}, author={Poyda, V. P. and Milaya, D. Ye. and Poyda, A. V. and Bryukhovetskiy, V. V. and Petrushenko, S. I. and Dukarov, S. V.}, year={2020}, month={Jul.}, pages={14-25} }