The role of Cr in the reactive synthesis of porous FeAlCr intermetallic compounds

This work prepared a series of porous FeAlCr intermetallic compounds with the Cr content ranging from 5 wt% to 20 wt% by a reactive synthesis method using element powders. These porous FeAlCr materials correspond to the B2-structured FeAl intermetallic (α2) that distinguishes them from the traditional FeCrAl solid-solution alloy (α1) porous materials. The exothermic behaviors, phase characteristics, pore structures and oxidation behaviors of porous FeAlCr with the variation of Cr content were systematically studied. The results showed that upon increasing the Cr content, the released heat during synthesis process was remarkably reduced, while the volume expansion, pore size and open porosity were increased in direct proportion. The linear changes in sample size and pore structure were ascribed to the preferential growth of Al4Cr phase. The oxidation behaviors of porous FeAlCr materials at 600 °C followed a parabolic-linear law, and their oxidation mass gain rates were much slower than those of other reported Ni-based and Fe–Cr alloys. This work proves that to a certain extent the high content of Cr is conducive to the controllable synthesis and high-temperature oxidation resistance of porous FeAlCr materials.