On the stress and temperature dependence of low temperature and high stress shear creep in Ni-base single crystal superalloys

D. Bürger, A. Dlouhý, K. Yoshimi, G. Eggeler

Research output: Contribution to journalArticlepeer-review

Abstract

In the present work, we investigate the stress and temperature dependence of low-temperature (750 ± 20 °C) and high-stress (300 ± 20 MPa) shear creep of a Ni-base single crystal superalloy. From continuous isothermal experiments and stress and temperature change tests the stress exponent n and the apparent activation energy Qapp of the phenomenological Sherby-Dorn equation were determined for the two macroscopic crystallographic shear systems (MCSS) [011¯](111) and [112¯](111). The activation parameters of creep, the stress exponents and the apparent activation energies were identified as 16 and 620 kJ/mol (MCSS: [011¯](111)) and 14 and 460 kJ/mol (MCSS: [112¯](111)). We show that during shear creep testing these phenomenological parameters do not change between the early (0.5–1% strain) and later stages of creep (4.5–5% strain), in contrast to what was observed for uniaxial tensile testing. The results are discussed in the light of what is known about stress and temperature dependencies of deformation rates in the creep literature and in view of the recent work by Bürger et al., 2020, who combined shear creep testing with analytical transmission electron microscopy to identify the elementary deformation mechanism, which governs low temperature and high stress creep.

Original languageEnglish
Article number139961
JournalMaterials Science and Engineering A
Volume795
DOIs
Publication statusPublished - 2020 Sep 23

Keywords

  • Activation energy
  • Dislocation mechanisms
  • Low-temperature high-stress creep
  • Ni-base superalloy single crystals
  • Shear creep deformation
  • Stress exponent

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

Fingerprint Dive into the research topics of 'On the stress and temperature dependence of low temperature and high stress shear creep in Ni-base single crystal superalloys'. Together they form a unique fingerprint.

Cite this