Anisotropic strain hardening following load reversal during high-temperature creep testing of superalloy single crystals

Carroll, Mark; Serin, K.; Eggeler, Gunther

doi:10.1016/j.msea.2004.03.098

Cited by 14 publications

(4 citation statements)

References 17 publications

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“…There were two microstructural results which could not have been easily obtained using uniaxial creep testing. Carrol et al [47] showed that the measured creep rate in double shear samples following a load reversal is considerably higher than the initial forward creep rate. Carroll et al [47] observed this for other materials too, but not to the extent seen in the Ni-base superalloy CMSX-4.…”

Section: Early Microstructural and Mechanical Resultsmentioning

confidence: 99%

“…Carrol et al [47] showed that the measured creep rate in double shear samples following a load reversal is considerably higher than the initial forward creep rate. Carroll et al [47] observed this for other materials too, but not to the extent seen in the Ni-base superalloy CMSX-4. A basis for this jump in reverse creep rate is grounded in the principle by which dislocations fill the c-channels in the early stages of creep.…”

Section: Early Microstructural and Mechanical Resultsmentioning

confidence: 99%

“…This Dislocations enter channels and deposit long interface dislocation segments. [47] (b) Dislocations from both c/c¢-interfaces from one c-channel approach each other on load reversal. [47] (c) Rafting reacts to superimposed bending stresses in the outer parts of the shear zones during h100i{010} shear testing.…”

Section: B Anisotropic Creep Stress Calculationsmentioning

confidence: 99%

“…[47] (b) Dislocations from both c/c¢-interfaces from one c-channel approach each other on load reversal. [47] (c) Rafting reacts to superimposed bending stresses in the outer parts of the shear zones during h100i{010} shear testing. [48] (d) Rafts form at 45 deg to the shear loading direction during h1À10i{111} shear creep testing.…”

Section: B Anisotropic Creep Stress Calculationsmentioning

confidence: 99%

See 3 more Smart Citations

On Shear Testing of Single Crystal Ni-Base Superalloys

Eggeler

Wieczorek

Fox

et al. 2018

Metall Mater Trans A

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Shear testing can contribute to a better understanding of the plastic deformation of Ni-base superalloy single crystals. In the present study, shear testing is discussed with special emphasis placed on its strengths and weaknesses. Key mechanical and microstructural results which were obtained for the high-temperature (T % 1000°C) and low-stress (s % 200 MPa) creep regime are briefly reviewed. New 3D stereo STEM images of dislocation substructures which form during shear creep deformation in this regime are presented. It is then shown which new aspects need to be considered when performing double shear creep testing at lower temperatures (T < 800°C) and higher stresses (s > 600 MPa). In this creep regime, the macroscopic crystallographic [11À2](111) shear system deforms significantly faster than the [01À1] (111) system. This represents direct mechanical evidence for a new planar fault nucleation scenario, which was recently suggested (Wu et al. in Acta Mater 144:642-655, 2018). The double shear creep specimen geometry inspired a micro-mechanical in-situ shear test specimen. Moreover, the in-situ SEM shear specimen can be FIB micro-machined from prior dendritic and interdendritic regions. Dendritic regions, which have a lower c¢ volume fraction, show a lower critical resolved shear stress.

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Section: Early Microstructural and Mechanical Resultsmentioning

confidence: 99%

Section: Early Microstructural and Mechanical Resultsmentioning

confidence: 99%