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

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• 作者：Ping  ; Han^a ;   ; ^{hanpingbetty@yahoo.com.cn} ; Yihui  ; Qi^b ; Jianting  ; Guo^b
• 关键词：NiAl alloy ; Directional solidification ; Superplasticity ; Creep
• 刊名：Journal of Materials Science & Technology
• 出版年：2011
• 出版时间：2011
• 年：2011
• 卷：27
• 期：5
• 页码：437-442
• 全文大小：1175 K

文摘

The microstructure, high strain rate superplasticity and tensile creep behavior of directionally solidified (DS) NiAI-Mo(Hf) alloy have been investigated. The alloy exhibits dendritic structure, where dendritic arm is NiAl phase, interdendritic region is Ni₃AI phase, and Mo-rich phase distributes in the NiAl and Ni₃AI 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¡Á10^? s^?. 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 NiAI-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.