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Title: Nanoscale precipitates as sustainable dislocation sources for enhanced ductility and high strength
Traditionally, precipitates in a material are thought to serve as obstacles to dislocation glide and cause hardening of the material. This conventional wisdom, however, fails to explain recent discoveries of ultrahigh-strength and large-ductility materials with a high density of nanoscale precipitates, as obstacles to dislocation glide often lead to high stress concentration and even microcracks, a cause of progressive strain localization and the origin of the strength–ductility conflict. Here we reveal that nanoprecipitates provide a unique type of sustainable dislocation sources at sufficiently high stress, and that a dense dispersion of nanoprecipitates simultaneously serve as dislocation sources and obstacles, leading to a sustainable and self-hardening deformation mechanism for enhanced ductility and high strength. The condition to achieve sustainable dislocation nucleation from a nanoprecipitate is governed by the lattice mismatch between the precipitate and matrix, with stress comparable to the recently reported high strength in metals with large amount of nanoscale precipitates. It is also shown that the combination of Orowan’s precipitate hardening model and our critical condition for dislocation nucleation at a nanoprecipitate immediately provides a criterion to select precipitate size and spacing in material design. The findings reported here thus may help establish a foundation for strength–ductility optimization through more » densely dispersed nanoprecipitates in multiple-element alloy systems. « less
Authors:
; ;
Award ID(s):
1709318
Publication Date:
NSF-PAR ID:
10159403
Journal Name:
Proceedings of the National Academy of Sciences
Volume:
117
Issue:
10
Page Range or eLocation-ID:
5204 to 5209
ISSN:
0027-8424
Sponsoring Org:
National Science Foundation
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