Reaction behavior and pore formation mechanism of TiAl-Nb porous alloys prepared by elemental powder metallurgy

摘要

Ti-48Al-6Nb (at.%) porous alloys are fabricated by elemental powder metallurgy to study the pore formation and propagation mechanism. Reactive diffusion, pore formation process, and pore characteristics of the porous TiAl-Nb alloys are investigated at different temperatures. It is found that the porous alloys exhibit a uniform, maze-like network skeleton, viz., a typical 2-TiAl_3/-TiAl fully lamellar microstructure. The reactive diffusivities between Ti and Al powders are dominant during the Ti-Al-Nb powder sintering. Gas release during sintering also plays an important role in the pore propagation and the compact expanding process. In addition, a pore-formation model is proposed to interpret the growth mechanism of pores and skeletons.