Effect of niobium content on irradiation microstructure and hardening in FeCrAl-based alloys

•The evolution of dislocation loop with niobium content in FeCrAl alloys was discussed.•The formation of laves phase resulted in the decrease of Mo content and the increase of Cr content in the matrix of the FeCrAl alloys.•Nb addition increased nanoindentation hardness and reduced irradiation hardening in the FeCrAl alloys .