On the issue of stability of the metastable $\omega$ phase in pseudo-single-crystalline zirconium

Pseudo-single-crystalline zirconium samples were tested in a Bridgman chamber at a temperature of 20, 70, 100, and 300$^\circ$C under the same loading conditions. The aim of these tests was to examine the possibility of preservation of the metastable $\omega$ phase at elevated temperatures. It was found that stable structural configurations emerge in the process of warm deformation as a result of formation of equilibrium interphase boundaries and oriented nucleation and growth of the $\omega$ phase. These configurations enhance the stability of the $\omega$ phase after cooling and load removal. Disperse zirconium hydride particles of a variable composition ($\delta$-ZrH$_{2-x}$) were identified in the sample tested at 300$^\circ$C. Its high hardness, which is comparable to that of the sample tested at room temperature, is attributable to the presence of these particles.