Активационные характеристики вязкоупругих свойств жаропрочного сплава на основе системы Ni-Co-Cr, упрочненного объемным азотированием

Abstract

The results of measurements of the high-temperature internal friction background of the heat-resistant alloy VZh171 in the initial state and after volume nitriding presented. The obtained data used to study the regularities of the transition from the elastic to the viscoelastic state of the material at elevated temperatures. Nitriding the alloy leads to an increase in the transition temperature to the viscoelastic state from 571 K (initial state) to 763 K (after nitriding). The values of activation energy of the high-temperature internal friction background obtained: U f = 0.63 ± 0.01 eV for the alloy VZh171 in the initial state and U f = 0.59 ± 0.01 eV for the alloy after volume nitriding. The activation energies U 0 of the processes responsible for the formation of the viscoelastic properties of the substance are estimated: U 0 ≈ 2.52 eV for the alloy in the initial state, U 0 ≈ 2.36 eV for the nitrided alloy. The obtained values U 0 correspond to the self-diffusion activation energy in nickel, the main component of the alloy matrix. The appearance of dispersed nitride phases in the matrix leads to a decrease in the activation energy of viscoelasticity processes by about 6%. Possible reasons for the change in the transition temperature and the activation energy of the viscoelastic state at moderately high temperatures as a result of nitriding discussed.