Microstructures and Creep Behavior of a Directionally Solidified NiAl-Fe(Nb) Multiphase Intermetallic Alloy

The microstructure and creep behavior of a DS NiAl-Fe(Nb) multiphase intermetallic alloy have been investigated. This alloyexhibits dendritic structure, in which dendritic arm isβ-(Ni,Fe)(Fe,Al) phase surrounded by interdendritic region ofγ'/γ phase.The results of the creep test indicated that all of the creep curves have similar characteristic, which is a short primary creepstage and a dominant steady state creep stage, and the creep strain ranges from 18% to 52%. The apparent stress exponentand the apparent activation energy were analyzed and discussed. The mechanism of the creep deformation was also analyzedby the observation of TEM.