Transformations of the Microstructure and Phase Compositions of Titanium Alloys during Ultrasonic Impact Treatment Part II: Ti-6Al-4V Titanium Alloy

Experimental and theoretical studies enabled the reveal of patterns microstructure formation in surface layer Ti-6Al-4V titanium alloy subjected to ultrasonic impact treatment. The mixed amorphous nanocrystalline structure 200 nm thick uppermost dioxide TiO2 was demonstrated using transmission electron microscopy. 5 µm intermediate containing ? grains, 50–60 lower fragmented ?-Ti grains with retained ? phase were also observed. refinement ?-Ti during treatment accompanied by orthorhombic (??) martensitic phase. Molecular dynamics simulation strains a vanadium-doped crystallite revealed striped dislocation substructures as well development reversible ??? transformations. Ab initio calculations atomic V-doped Ti crystallites ?, or ?? phases carried out. On basis results experimental observations, molecular ab mechanism proposed, which associated strain-induced ???? transformations presence oxygen. role electronic subsystem discussed.