Size-affected single-slip behavior of René N5 microcrystals

P. A. Shade, M. D. Uchic, D. M. Dimiduk, G. B. Viswanathan, R. Wheeler, H. L. Fraser

Research output: Contribution to journalArticleResearchpeer-review

26 Citations (Scopus)

Abstract

Microcompression testing was conducted on the cast single crystal nickel-base superalloy René N5. Microcrystals were selectively fabricated from either dendrite core or interdendritic regions. The compression axis was oriented for single-slip deformation and microcrystal diameters ranged from 2.5 to 80. μm. All microcrystals displayed several hallmarks of size-affected plastic flow, including a size-affected and stochastic flow-stress and initial strain hardening rate, as well as an intermittent flow response. The magnitude of size-affected flow-stress scaling behavior was dependent upon the plastic strain level of the flow-stress measurement, with increasing size-dependence for increasing strain levels. TEM analysis demonstrated the activation of multiple slip-systems, despite the microcrystals being oriented for single-slip deformation. Zig-zag slip was also observed in microcrystals that achieved flow stresses of ∼1300. MPa or higher. For microcrystals fabricated within interdendritic regions the flow-stress values are, on average, lower compared to dendrite core microcrystals. This difference in flow-stress is especially pronounced for microcrystals which are 5. μm in diameter. The microcrystal diameter for which bulk-like properties are estimated to be observed is approximately 350. μm, which is approaching the measured primary dendrite arm spacing for this crystal (430. μm).

Original languageEnglish
Pages (from-to)53-61
Number of pages9
JournalMaterials Science and Engineering A: Structural Materials: Properties, Microstructure and Processing
Volume535
DOIs
Publication statusPublished - 15 Feb 2012
Externally publishedYes

Keywords

  • Microcompression
  • Nickel-based superalloys
  • Size effect

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