In support of multiscale modeling of microstructural evolution for computational materials design, X-ray line broadening measurements of dislocation cell size and matrix coherency strain are integrated with small-angle neutron scattering measurements of M2C precipitate size during secondary hardening of ultrahigh-strength Ni-Co martensitic steels. In addition to the retarding effect of Co in solution, M2C precipitation further retards dislocation recovery, and the effect is greater with the finer-scale precipitation associated with higher thermodynamic driving force. An increase in microstrain amplitude during early precipitation is attributed to carbide coherency strain. A subsequent decrease occurring at or before peak hardness is interpreted as the onset of coherency loss. This supports similar critical particle sizes of approximately 30 angstroms diameter for coherency loss and the shear-to-bypass transition in strengthening behavior.
|Original language||English (US)|
|Number of pages||10|
|Journal||Proceedings of the TMS Fall Meeting|
|State||Published - Dec 1 1999|
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