The microstructure and high temperature tensile creep behavior of directionally solidified NiAl-28Cr-5Mo-1Hf alloy have been investigated. The alloy is composed of NiAl matrix, Cr(Mo) phase and a small amount of Ni2AlHf (Heusler) phase which discontinuously distributed at NiAl and Cr(Mo) phase boundaries. All of the creep curves under different temperatures and loadings have similar shape of a short primary creep and dominant steady creep stages, the creep strain is relatively large, and the microstructure of the post-creep deformation is nearly the same as that of pre-creep deformation. The creep deformation is controlled by dislocation climb resulting from lattice self-diffusion. The creep fracture data follow the Monkman-Grant relationship.
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