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Theory of Worksoftening in High‐Performance Alloys
Author(s) -
KuhlmannWilsdorf Doris,
Wilsdorf H. G. F.
Publication year - 1992
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2221720122
Subject(s) - materials science , ductility (earth science) , metastability , yield (engineering) , dislocation , flow stress , stress (linguistics) , light emitting diode , metallurgy , composite material , optoelectronics , alloy , chemistry , creep , linguistics , philosophy , organic chemistry
In conventional alloys ductility decreases with rising flow stress to negligible values at some maximum yield stress (τ m ), whereas high‐performance alloys, e.g. formed throgh mechanical alloying or nano‐powders, can have much higher yield stresses with ductility, but tend to worksoften. A simple theory is presented, based on the LEDS concept, to account for both of these behaviors: The flow stress is τ = τ 0 + const √ϱ with ϱ the dislocation density, and the workhardening coefficient is θ ≈ dτ 0 /dγ + C β with β the rate of glide dislocation trapping. β depends on the specific LEDS formed but always decreases with stress and can become negative for τ > τ m at artificially high ϱ. Worksoftening results when unconventional manufacturing methodes have produced LEDS with metastable ϱ and/or τ 0 values that are higher than conform to the LEDS generated through the conventional straining conditions in testing or use.