Fabrication, pore structures and mechanical properties of (TiB2-Al2O3)/NiAl porous composites

Abstract

Open-celled porous (TiB2-Al2O3)/NiAl composites were successfully fabricated by using spherical carbamide as space holders via self-propagating high-temperature synthesis (SHS). Effects of 10Al-3B2O3-3TiO2 contents (0-20 wt%) on the pore structures and the quasi-static compressive behaviors of the resultant materials were investigated. The porous (TiB2-Al2O3)/NiAl composites exhibit composite pore structure consisting of homogeneously distributed and interconnected millimeter pores and micropores. The millimeter pores virtually inherit the shape and size of carbamide particles, while the pore size of micropores increases with increasing the 10Al-3B2O3-3TiO2 content. Depending on the volume fraction of the carbamide, the porosity of the porous materials can be easily controlled in a range of 55%-85%. When the porosity is about 72%, the compressive strengths of porous NiAl and porous (TiB2-Al2O3)/NiAl composite with 15% 10Al-3B2O3-3TiO2 in green compact are 19 and 32 MPa, and the corresponding strains are 2.9% and 5.7%, respectively. Furthermore, the quasi-static compressive behavior of porous (TiB2-Al2O3)/NiAl composites can be estimated by Gibson-Ashby model.