Compressive deformation behavior of porous γ-TiAl with directional pores

Lotus-type porous Ti52Al48, possessing elongated pores aligned in one direction, was fabricated by a continuous zone melting technique under pressurized hydrogen/helium atmospheres. Compression tests were carried out on specimens with various porosities and with loading directions parallel and perpendicular to the elongated pore direction. The compressive properties of lotus TiAl significantly differ from those of conventional lotus metals with ductile matrix. Deformation and initial cracks are observed around the pores, and they progress around the pores locally. Therefore, the densification of the specimen does not occur. This is due to the brittle matrix, which is sensitive to local large stress concentration. Thus, it is concluded that compressive properties of lotus metals depend not only on macroscopic pore structure but also on the degree of ductility of matrix.