Calorimetry and Peculiarities of Reverse ω → α Phase Transformation in Zr and Ti Pseudo-Single Crystals

Differential scanning calorimetry, X-ray diffraction analysis, transmission electron microscopy, and microhardness measurements are used to study the reverse ω → α phase transformation in titanium and zirconium, which were subjected to deformation in a Bridgman chamber under close loading conditions in order to obtain additional data on the degree of stability of the studied metals. It was found that, despite the qualitative similarity of heat release processes that occurred in the metals under study, which are recorded by differential scanning calorimetry, the reverse phase transformation in titanium, in contrast to that in zirconium, is realized at lower temperatures and within narrower temperature range over the whole range of preliminary true strain. It was found that the characteristics, such as the temperature of the onset of reverse phase transformation and value of released thermal energy are stabilized on reaching the certain true strain (е ≈ 9), when the mixed nano- and submicrocrystalline structure forms in both the metals, in which deformation defects and extensive interfaces make the maximum energy contribution to the system.