Interaction between nickel base superalloy ZhS6U used as a friction processing tool for in-situ synthesis of intermetallics in Ti6Al4V and this titanium alloy metal has been studied. Severe abrasion-adhesion wear was localized on the tool’ pin areas while shoulder was protected by mechanically mixed layer. Generation of titanium enriched mechanically mixed layers (MML) on the tool's surface was observed whose chemical and phase compositions corresponded to those of Ti2Ni and Ni4Ti3 intermetallic compounds. Fine-crystalline transition layer (TL) was found below the MML which contained high amount of tungsten in the form of fine MC carbide network. Dissolution of initial M6C carbides and diffusion of their components to the MML where new MC-type carbide network formed after stopping the FSP. The MML fragments detached from the tool surface and then were intermixed with the titanium alloy stir zone.