Kinetic Characteristics of Nitriding of Zr–1% Nb Alloy

We study the kinetic characteristics of nitriding of thin-sheet (~ 1 mm) samples of Zr–1% Nb alloy treated in a nitrogen atmosphere (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ {P}_{{\textrm{N}}_2}={10}^5\textrm{Pa} $$\end{document}) in broad temperature (T = 550; 650; 750; 850 and 950°С) and time (τ = 1; 5 and 10 h) ranges. It is shown that the process of nitriding of the analyzed alloy obeys a law close to a parabolic dependence (n ≈ 2). It is discovered that the activation energy of nitriding of the alloy within the temperature range 550–950°C is equal to 131.8 kJ/mole. The microstructure of the subsurface layer of the alloy after nitriding is analyzed. The distribution of the surface microhardness of Zr–1% Nb alloy is determined. The diagrams of intensity of the phase reflexes of α-Zr and ZrN on the surface of alloy after treatment in a nitrogen atmosphere are constructed.