Structural-Phase State of the Surface Layer of Titanium Alloy Doped with Copper Atoms and Its Thermal Stability

Results of structure, phase and element composition, and microhardness of the surface layer of Ti–6Al–4V alloyed by copper atoms under the action of compression plasma flows generated in nitrogen atmosphere are presented in this work. The findings showed that growth of the energy density absorbed by the surface layer in the region of 26–43 J/cm2 led to diminishing of copper concentration from 20 to 4 at % in the alloyed layer. An alloyed layer with thickness of ~18 μm contained CuTi2 and Cu3Ti2 intermetallides. Nitride δTiN was formed on the surface of the alloyed layer. Annealing at 750°С resulted in Cu3Ti2 decomposition.