Pore formation during reactive sintering of extruded titanium - aluminium powder mixtures

A powder mixture Ti-49 at.% Al was extruded at room temperature. Swelling due to phase transformation during annealing was studied using differential scanning calorimetry and dilatometry. It is the result of several processes: (i) Kirkendall pores during solid state interdiffusion, (ii) macro-pores during the reaction of liquid aluminium and solid titanium, (iii) inter-diffusion of Al 3 Ti and pure titanum forming the intermetallic phases γ-TiAl and α 2 -Ti 3 Al. Swelling is anisotropic due to the elongated titanium particles. Sintering occurs at higher temperatures depending on the microstructure after Al 3 Ti formation