Precipitation behavior of Fe2Nb Laves phase on grain boundaries in austenitic heat resistant steels

Present paper describes the microstructures of Fe-20Cr-30Ni-2Nb (at%) alloys with and without the addition of 0.03%B after aging. Microstructure was investigated using XRD, SEM, EPMA and TEM. Particular attention was paid to Fe2Nb Laves phase present on grain boundaries that may improve creep resistance of this alloy. Furthermore, effects of Boron on precipitation of Fe2Nb Laves phase on grain boundaries were also explored. Precipitates of Laves phase on grain boundaries in the Boron doped alloy were finer and higher in number density than those in the base alloy. Grain boundary segregation of Boron in the alloy was observed, which probably promotes precipitation of Laves phase on grain boundaries, and thereby enhances the creep resistance of the alloy.