Activation Parameters of Viscoelasticity Formation of Nitride-Hardened Refractory Alloy.

The paper presents the measurement results of the internal friction high temperature background for the VZh171 refractory alloy before and after its nitridation. The obtained data are used to study mechanisms of the alloy transition from the elastic to viscoelastic state at elevated temperatures. The nitridation process leads to a rise of the transition temperature from 571 K (initial state) to 763 K (after nitridation). The activation energy of the internal friction high temperature background is 0.63±0.01 and 0.59±0.01 eV before and after the bulk nitridation, respectively. The activation energy of processes responsible for the formation of viscoelastic properties, is ≈2.52 and ≈2.36 eV before and after the bulk nitridation, respectively. These values correspond to the self-diffusion activation energy in nickel, the main component of the alloy matrix. The presence of the dispersed nitride phase in the matrix decreases the activation energy of viscoelastic processes by about 6%. Possible reasons are considered for changes in the nitridation-induced transition temperature and activation energy of viscoelastic processes at moderately high temperatures. [ABSTRACT FROM AUTHOR]