THE INFLUENCE OF ULTRAFINE-GRAINED STATE OF Zr-1 wt.% Nb AND Ti-45 wt.% Nb ALLOYS ON THEIR THERMOPHYSICAL PROPERTIES AND ENERGY DISSIPATION AND ACCUMULATION DURING DEFORMATION

摘要

The results of a study of thermal conductivity and specific heat capacity of Zr - 1 wt.% Nb and Ti - 45 wt.% Nb alloys in coarse-grained and ultrafine-grained states are presented. The influence of the utrafinegrained state on the thermophysical properties and the processes of energy dissipation and accumulation during deformation of the alloys are estimated. It is shown that the formation of an ultrafine-grained state in a Zr - 1 wt.% Nb alloy by abc-pressing and subsequent rolling leads to a decrease in its thermal conductivity and specific heat capacity by 10 and 20%, respectively, due to substructural strengthening under severe plastic deformation. It is found out that thermal conductivity and specific heat capacity of the ultrafine-grained Ti - 45 wt.% Nb alloy increase by 7.5 and 5%, respectively, due to dispersion hardening of the omega phase by nanoparticles and formation of a new alpha phase. It is established that the ultrafine-grained structure has a significant influence on the energy dissipation and accumulation during plastic deformation, which in turn depend on their thermophysical characteristics and on the structural and phase states.