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Model of diffusion coarsening of the raft structure in single crystals of nickel-base superalloys

✍ Scribed by Y. Mishin; N. Orekhov; I. Razumovskii; G. Alyoshin; P. Noat

Publisher
Elsevier Science
Year
1993
Tongue
English
Weight
496 KB
Volume
171
Category
Article
ISSN
0921-5093

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✦ Synopsis

The creep resistance of nickel-base superalloy single crystals is determined by the stability of the raft structure that forms at elevated temperatures under applied tensile stresses. This paper proposes a mechanism of stabilization and coarsening of the raft structure, based on the analysis of the balance between the elastic energy and the y-y' interphase energy. An abrupt coarsening of the raft structure, observed at the final stage of a creep test, is caused by unlimited diffusioncontrolled growth of hole-like macrodefects in ~,' layers of the structure. Based on this model, numerical estimations of the coarsening kinetics have been made, using structural and energetic characteristics of a commercial superalloy. The results arc consistent with typical creep test results for nickel-base superalloys.

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