Registration Number
0217U002607,
0114U001300
, R & D reports
Title
Development of long-term strength physical fundamentals for HCP modified alloys
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Head
Tkachenko Volodimir Grigorovich,
Registration Date
28-04-2017
Organization
Frantzevich Insitute for Materials Science Problems of the Ukranian National Academy of Sciences
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The object of study - the effect of modifying and nano-phase strengthening of the ZrO2 nanoparticles in the short-term and long-term physical and mechanical properties of zirconium alloys. The aim is to study the physical nature of microplastic deformation and to establish the most probable dislocation mechanisms responsible for the inhibition of dislocations in a wide range of parameters (T, s, t), and on this base to develop the physical fundamentals of long-term strength of the nano-strengthening alloy with HCP structure. Research methods - X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, the study of hardness, standard tensile testing, creep, stress relaxation technique. A method of introducing ZrO2 nanoparticles being smaller than 5 nm in molten metal alloy systems Zr-Nb-Sn was proposed. Addition of nanoparticles (1.2 wt. %) in the Zr-Nb-Sn alloys causes additional creep resistance as well as increase of the tensile strength and yield strength at 400 °C not less than 50%. The steady creep rate is reduced by 2 - 3 times. Effect of the concentration Sn atoms and ZrO2 particles on change creep resistance at 400 °C was determined for the first time using resistance diagrams of zirconium alloys. It was found that nanophase strengthening of Zr-Nb-Sn alloys is controlled by thermally activated dislocation mechanism rather than athermal Orovan mechanism. Theoretical calculations of the strength for Zr-Nb-Sn, and Zr-Nb-Sn-ZrO2 alloy systems indicate the activation of the thermally activated mechanism of the dislocation by-pass nanoparticles and are consistent with the Art-Wilkinson concept connecting the braking-out of climbing dislocations from the elastic stress field at the interfaces. The results can be used to develop new zirconium alloy fuel element with a higher heat resistance at temperatures of 450 - 500 °C.
Product Description
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Малка Олександр Миколайович
Щерецький Анатолій Олександрович
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2020-04-02
