Titanium foams produced by solid-state replication of NaCl powders

Open-celled titanium foams were fabricated by vacuum hot pressing of a blend of Ti and NaCl powders followed by NaCl removal in water. Densification kinetics of the Ti/NaCl blends are measured at 780 °C at various pressures (30–50 MPa), NaCl volume fractions (30–70%) and NaCl powder sizes (50–500 μm). As compared to pure Ti powders, densification kinetics of the blends is faster for relative densities below 92% due to rapid deformation of the NaCl powders. After dissolution, the flattened shape of the NaCl powders is replicated in the pores, resulting in an anisotropic porous structure. The foams exhibit good compressive strengths (e.g., 102 MPa for 50% porosity and 28 MPa for 67% porosity), low Young moduli (e.g., 29 GPa for 51% porosity) and ductile behavior up to compressive strain >60%.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideResearch highlights▶ NaCl/Ti powders blends are densified at 780 °C at 30–50 MPa for 30–70% NaCl powders with 50–500 μm size. ▶ NaCl/Ti blends densify faster than pure Ti because NaCl is much weaker than Ti. ▶ Pores in Ti created by NaCl dissolution show flattened shapes due to NaCl deformation. ▶ A Ti foam with 50% pores has a 29 GPa modulus, a 102 MPa yield stress and good compressive ductility.