scholarly journals STEM Optical Sectioning for Imaging Screw Dislocations Core Structures in BCC Metals

2016 ◽  
Vol 22 (S3) ◽  
pp. 1932-1933 ◽  
Author(s):  
David Hernandez-Maldonado ◽  
Hao Yang ◽  
Lewys Jones ◽  
Roman Gröger ◽  
Peter B Hirsch ◽  
...  
Keyword(s):  
Optical Sectioning ◽  
Screw Dislocations ◽  
Bcc Metals

scholarly journals Evaluation of Aberration-corrected Optical Sectioning for Exploring the Core Structure of ½[111] Screw Dislocations in BCC Metals

2017 ◽  
Vol 23 (S1) ◽  
pp. 432-433
Author(s):  
D. Hernandez-Maldonado ◽  
R. Groger ◽  
Q. M. Ramasse ◽  
P. B. Hirsch ◽  
P.D. Nellist
Keyword(s):  
Core Structure ◽  
Optical Sectioning ◽  
Screw Dislocations ◽  
The Core ◽  
Bcc Metals ◽  
Aberration Corrected

scholarly journals Repulsion leads to coupled dislocation motion and extended work hardening in bcc metals

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
K. Srivastava ◽  
D. Weygand ◽  
D. Caillard ◽  
P. Gumbsch
Keyword(s):  
Work Hardening ◽  
Activation Barrier ◽  
Dislocation Motion ◽  
Dislocation Dynamics ◽  
Additional Contribution ◽  
High Symmetry ◽  
Screw Dislocations ◽  
Bcc Metals ◽  
Kink Pair ◽  
Extended Work

Abstract Work hardening in bcc single crystals at low homologous temperature shows a strong orientation-dependent hardening for high symmetry loading, which is not captured by classical dislocation density based models. We demonstrate here that the high activation barrier for screw dislocation glide motion in tungsten results in repulsive interactions between screw dislocations, and triggers dislocation motion at applied loading conditions where it is not expected. In situ transmission electron microscopy and atomistically informed discrete dislocation dynamics simulations confirm coupled dislocation motion and vanishing obstacle strength for repulsive screw dislocations, compatible with the kink pair mechanism of dislocation motion in the thermally activated (low temperature) regime. We implement this additional contribution to plastic strain in a modified crystal plasticity framework and show that it can explain the extended work hardening regime observed for [100] oriented tungsten single crystal. This may contribute to better understanding the increase in ductility of highly deformed bcc metals.

The position of screw dislocations in BCC metals

1980 ◽  
Vol 14 (9) ◽  
pp. 983-986 ◽  
Author(s):  
Gunther Schoeck
Keyword(s):  
Screw Dislocations ◽  
Bcc Metals

scholarly journals Unusual activated processes controlling dislocation motion in body-centered-cubic high-entropy alloys

2020 ◽  
Vol 117 (28) ◽  
pp. 16199-16206 ◽  
Author(s):  
Bing Chen ◽  
Suzhi Li ◽  
Hongxiang Zong ◽  
Xiangdong Ding ◽  
Jun Sun ◽  
...  
Keyword(s):  
Activation Barrier ◽  
Dislocation Motion ◽  
Atomistic Simulations ◽  
High Entropy Alloys ◽  
Body Centered Cubic ◽  
Screw Dislocations ◽  
High Entropy ◽  
Bcc Metals ◽  
Edge Dislocations ◽  
Rate Limiting

Atomistic simulations of dislocation mobility reveal that body-centered cubic (BCC) high-entropy alloys (HEAs) are distinctly different from traditional BCC metals. HEAs are concentrated solutions in which composition fluctuation is almost inevitable. The resultant inhomogeneities, while locally promoting kink nucleation on screw dislocations, trap them against propagation with an appreciable energy barrier, replacing kink nucleation as the rate-limiting mechanism. Edge dislocations encounter a similar activated process of nanoscale segment detrapping, with comparable activation barrier. As a result, the mobility of edge dislocations, and hence their contribution to strength, becomes comparable to screw dislocations.

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