Effect of Nb on pore structure and tensile property of Ti-48Al cellular alloy

TiAl based alloys have been investigated traditionally as potential high temperature structural materials. Another interesting field where TiAl based cellular alloys were fabricated by elemental powder metallurgy (EPM) is shown in this study. The effects of Nb addition forms (Nb elemental powder and Nb-Al alloying powder) and contents on pore structures and tensile properties of Ti-48Al cellular alloy were investigated. It was found that the phases identified are γ-TiAl and α2-Ti3Al when Nb content is less than 2%, and pore structures of Ti-48Al-2Nb alloy are similar to those of Ti-48Al cellular alloy for both Nb addition forms. When Nb content is beyond 2%, an additional AlNb2 phase is observed, and pore structures also change. Lots of particles form on the surface of the skeleton for adopting Nb elemental powder, and micropores appear along with big pores for adopting Nb-Al alloying powder. With the increase of Nb content, tensile strength rapidly decreases for adopting Nb elemental powder. However, the contrary phenomenon happens for the other form.