Search academic texts

Information × Registration Number 0308U001424, 0106U003115 , R & D reports Title Research of relaxation processes in conditions of plastic and superplastic deformation of polycrystalline samples popup.stage_title Дослідження закономірностей розвитку тріщин і ротаційної структури в умовах пластичної деформації двовимірних полікристалів алюмінію Head Sirenko Anatoliy Fedotovich, Registration Date 04-02-2008 Organization Kharkov Natuional university named after V.N.Karazin popup.description2 Object of examinations - two-dimentional (ІparquetІ structure) aluminium polycrystals, two-dimentional aluminium polycrystals with TiN thorough covering, cast Pb-62% Sn eutectic alloy. Methods of investigation - mechanical test under active tension conditions at a room temperature and under creep conditions, X-ray method of investigation (Lauer method, nonspecular scattering of X-ray), special technique of observation of structural changes during a plastic deformation of aluminium polycrystal which based on using white light scattering by surface of previously pickled specimen, optical and scanning electron microscopy, method of internal friction. The orientation changes arising during a plastic deformation of two-dimentional aluminium polycrystal were studied. Three fundamentally different types of the orientation changes which connected with a sliding and bring about formation of primary and secondary reorientation bands are discovered. The inter-relation between conditions of crack origination and development and rotational effects arising during a plastic deformation and crystallographic orientation of in-dividual initial grains is founded. The influence of TiN thorough strain-hardening covering on a plastic defor-mation development in two-dimentional aluminium polycrystals and mechanical data of strain-hardening specimens is studied. It is established that presence of TiN covering almost completely blockade development of rotational mode as one way of plastic deformation, result in decrease of plasticity of investigated specimens, essentially increase conventional yield strength and practically do not influence on breaking point. The structurally-phase changes in Pb-62% Sn eutectic alloy were studied under superplasticity conditions. The fact of anomalous decrease of crystal viscos-ity and active development of dislocationally-diffusion flow under superplasticity conditions is founded for the first time. It is bounded up with origination of high internal stress level caused by interaction of plastic deformation processes and phase transformations in initially metastable alloy. Results of the research are used for clarification of physical essence of de-formation processes in polycrystals, which exploit under different conditions of stress action. The forecast assumption on further development of test subject - further ex-tended study of physical nature of main mechanisms, which control plastic and su-perplastic flow in polycrystals. Product Description popup.authors popup.nrat_date 2020-04-02 Close