Skoryk M. Effect of compressive strain rate on microstructure evolution and mechanical behavior of titanium-based alloys

The thesis is devoted to the study of the behavior of titanium alloys of various types and with different microstructures under conditions of dynamic compressive loading. The experimental studies of deformation processes during compression with rates varying in a wide range were carried out for three different materials: VT1-0, Ti-6Al-4V, and Ti-15Mo which differ in phase composition and microstructure. The study of the microstructure of the teste samples made it possible to find out the main mechanisms of deformation. A significant dependence of the mechanical behavior of the studied materials on the type and dispersion of the initial microstructure and its anisotropy was established. In particular, for the Ti-6Al-4V alloy, the fine-grained globular microstructure showed the highest tolerance to high strain rates compared to other microstructural states. It was also shown that the deformation of titanium alloys at high rates has a localized character at the microlevel, in contrast to quasi-static deformation which proceeds almost uniformly. Titanium alloys have high specific values of deformation energy compared to some other structural materials under conditions of dynamic loading at high rates. Key words: titanium alloys, deformation mechanism, dynamic load, microstructure, mechanical behavior, adiabatic shear bands.