Microstructure and Elevated Temperature Tensile Behavior of Directionally Solidified Ni-rich NiAl-Mo（Hf） Alloy

Ping Han1), Yihui Qi2) and Jianting Guo2) 1) Department of Physics, Bohai University, Jinzhou 121013, China 2) Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China

摘 要：The microstructure, high strain rate superplasticity and tensile creep behavior of directionally solidified （DS） NiAl-Mo（Hf） alloy have been investigated. The alloy exhibits dendritic structure, where dendritic arm is NiAl phase, interdendritic region is Ni3Al phase, and Mo-rich phase distributes in the NiAl and Ni3Al phases. The alloy exhibits high strain rate superplastic deformation behavior, and the maximum elongation is 104.2% at 1373 K and strain rate of 1.04×10-2 s-1. The balance between strain hardening （by dislocation glide） and strain softening （by dynamic recovery and recrystallization） is responsible for the superplastic deformation. All the creep curves of the DS NiAl-Mo（Hf） alloy have similar shape of a short primary creep and dominant steady creep stages, and the creep strain is great. The possible creep deformation mechanism was also discussed. The creep fracture data follow the Monkman-Grant relationship.

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