Mechanism of Intermediate Temperature Embrittlement of Ni and Ni-based Superalloys

Ni-based superalloys play an important role in aircraft engine propulsion. However, many experiments demonstrated that these alloys as well as Ni always show ductility loss at intermediate temperature, which constrains further development. A comparison of published papers by various authors reveals...

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Bibliographic Details
Published in:Critical reviews in solid state and materials sciences 2012-07, Vol.37 (3), p.181-214
Main Authors: Zheng, Lei, Schmitz, Guido, Meng, Ye, Chellali, Reda, Schlesiger, Ralf
Format: Article
Language:English
Subjects:
Applied sciences
applied stress
Brittleness
Ductility
Exact sciences and technology
fracture mode
Fractures
grain boundary segregation
intermediate temperature embrittlement
Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology
Metals. Metallurgy
Ni-based superalloy
Nickel alloys
Strain rate
Superalloys
Temperature effects
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Summary:Ni-based superalloys play an important role in aircraft engine propulsion. However, many experiments demonstrated that these alloys as well as Ni always show ductility loss at intermediate temperature, which constrains further development. A comparison of published papers by various authors reveals considerable differences in understanding the mechanism of intermediate temperature embrittlement. To clarify this situation, the present article first confirms the generality of intermediate temperature embrittlement of Ni and Ni-based alloys by the experimental results reported in the literature. The existing interpretations of the mechanism are then outlined. Based on the generality, these interpretations are discussed through the representative investigations on intermediate temperature embrittlement. It is shown that the mechanism of intermediate temperature embrittlement has not been satisfactorily explained yet and "nonequilibrium interface segregation" of impurities taking into account the effect of strain rate may be the origin of intermediate temperature embrittlement of Ni and Ni-based superalloys. Future research directions aiming at the reason of abnormal fracture mode, the effect of the state of applied stress, the influence of strain rate, and the development of the theory nonequilibrium grain boundary segregation, are suggested to provide a complete understanding of intermediate temperature embrittlement.
ISSN:1040-8436
1547-6561
2331-4583
DOI:10.1080/10408436.2011.613492