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Defect structure in nickel single crystals in dependence on the cyclic deformation prehistory
Author(s) -
Hoffmann E.,
Kleinert W.,
Schmidt W.
Publication year - 1983
Publication title -
crystal research and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.377
H-Index - 64
eISSN - 1521-4079
pISSN - 0232-1300
DOI - 10.1002/crat.2170180106
Subject(s) - dislocation , deformation (meteorology) , nickel , materials science , nucleation , crystallography , strain (injury) , electrical resistivity and conductivity , amplitude , composite material , condensed matter physics , chemistry , metallurgy , optics , physics , organic chemistry , medicine , quantum mechanics
The development of the dislocation structure in nickel single crystals push‐pull fatigued at room temperature is investigated for different deformation types using electrical resistivity measurements and results of TEM observations. The dislocation density in the bundles of the matrix is higher after changing the strain amplitude from region A to region B (CD AB ‐type) of the cyclic stress‐strain curve ( N dB ≈ 1.6 ≈ 10 15 m −2 ) than after virginal deformation in region B (VD B ‐type) especially at higher strain amplitudes ( N dB ≈ 0.75 ≈ 10 15 m −2 ). Increasing the strain amplitude within region B (CD BB ‐type) does not change N dB . The farther development of the matrix structure after reaching the v H ‐minimum during the VD B ‐type of deformation suggests the action of the „formation and dissolution” – mechanism, whereas the CD BB ‐type causes the „cord”‐mechanism of the PSB nucleation.