Reactive synthesis of porous FeAlCr intermetallics with enhanced mechanical property and oxidation resistance by introducing yttrium borides

Abstract

This work presented the delightful improvements of mechanical property and oxidation resistance of porous FeAlCr intermetallics by introducing yttrium borides during reactive synthesis. The exothermic effect, volume swelling, pore structure evolution and phase transformation were detailedly investigated to clarify the role of yttrium borides on synthesis process. The results showed that yttrium borides could take part into the diffusion reactions around Al-melting point temperature and at elevated temperatures above 1100 °C. It was found that boron (B) was dissolved in FeAl matrix and segregated on grain boundaries; meanwhile, most of yttrium (Y) was enriched on the surface layer of porous skeleton. The tensile tests demonstrated that the strength and ductility of porous FeAlCr materials modified with 0.5–2.0 wt% yttrium borides were significantly improved and the optimal content was ~1.0 wt%. Porous FeAlCr materials modified with Y and B also showed an enhanced oxidation resistance at 800 °C due to the easier formation of stable α-Al2O3 scales.