Characterization of interdiffusion growth of aluminized layer on Ti alloys

During annealing on the surface of the Ti, Ti-4%Al-1%Mn and Ti-4%Al-3%Mo-1%V samples coated with Al films, different aluminide phases were formed successively as the result of reactions between Ti and Al. The structural evolution of the overlayers formed on the substrates during annealing depended on the thickness of the Al film, and the microstructure and chemical composition of the initial substrate. For thicker Al films, thicker overlayers were formed on the surface. Thicker overlayer required more time for its recrystallisation and microstructural transformation. The reactions occurred faster on the substrates with fine-grained microstructure than on the ones with lamellar structure. Chemical composition of substrates had a great effect on the diffusion transformation of overlayers. Reactions occurred faster on the Ti-4%Al-1%Mn samples than on the Ti and Ti-4%Al-3%Mo-1%V ones. After the elimination of the overlayer a fine plate microstructure was formed.