Effect of Nb element on mechanical properties and oxidation properties of AlFeCrNi2.5 alloy in a wide temperature range

The xNb/AlFeCrNi 2.5 alloys contained 0, 0.1, 0.15, 0.2, and 0.3 wt.% Nb were prepared by vacuum arc melting. The microstructure, wide temperature range mechanical properties, and cyclic oxidation behavior at 750°C were investigated. Microstructural analysis revealed a dual-phase structure composed of face-centered cubic (FCC) and body-centered cubic (BCC) phases. With the increasing of Nb content, the hardness, wide temperature range mechanical properties and cyclic oxidation resistance significantly improved. This enhancement due to the Nb promotes the slip deformation in the BCC structure, and boosts the strength and toughness of the alloy. At the same time, Nb can be dissolved into the FCC structure to enhance solid solution strengthening, this further improve the high-temperature mechanical properties of the alloy. Additionally, the oxidation mechanism of this series of alloys has been revealed, and Nb significantly improving the oxidation resistance of the xNb/AlFeCrNi 2.5 alloy. The Al 2 O 3 and Nb 2 O 5 are formed on the surface of alloys, which can effectively prevent the O from diffusing into the interior of the alloy.