Measurement of internal friction of Zr–1%Nb alloy after oxidation and nitriding

Abstract

This paper presents results of research of the Zr–1% Nb alloy using internal friction on sheet samples after oxidation due to leakage of air into the measurement facility, as well as after nitriding in an atmosphere of technical nitrogen. The measured temperature dependences of internal friction have been separated into partial maxima with the calculation of the effective activation energy according to the Wert-Marx formula. The purpose of the work is to detect the maxima of the internal friction of interstitial impurities in the alloy. It has been established that the oxygen maximum in successive measurements has activation energy 225, 222, 204 kJ/mol, and the nitrogen maximum has 234–236 kJ/mol. After lengthy high-temperature measurements, a carbon maximum appeared with activation energy 165 kJ/mol. For the grainboundary maximum activation energy from 197 to 203 kJ/mol was obtained for different samples, while the maximum height monotonously decreased with oxidation. These results for the Zr–1% Nb alloy were obtained for the first time and can be useful in corrosion tests of zirconium alloys.