Investigating the diffusion behavior in the Ti-Fe, Ni-Ti, Ti-Al, and Ni-Al binary systems during solid-state synthesis of intermetallic compounds via mechanical alloying

This study examines the solid-state synthesis of several binary intermetallic compounds, including Ti-Fe, Ni-Al, Ni-Ti, and Ti-Al, using mechanical alloying. The effects of mechanical alloying were examined, focusing on solid-state diffusion, phase formation, and mechanical stress. Microstructure analysis revealed the formation of lamellar structures during the initial stage of the mechanical alloying process. The size of these lamellar structures was used to calculate the diffusion coefficients. The apparent diffusion rates for several intermetallic formations were estimated and it was observed that the diffusion coefficient during the mechanical alloying process is about 1–2 orders higher than the diffusion coefficient obtained via high temperature synthesis. The microstructure and hardness of the intermetallic alloys were significantly improved through mechanical alloying, facilitated by the formation of intermetallic phases and the high-density defect microstructure. The role of lattice modification and crystalline size in the diffusion and microhardness behaviors of the nanoparticles were also highlighted.