Direct observation of dual-step twinning nucleation in hexagonal close-packed crystals

Design and processing of advanced lightweight structural alloys based on magnesium and titanium rely critically on a control over twinning that remains elusive to date and is dependent on an explicit understanding on the twinning nucleation mechanism in hexagonal close-packed (HCP) crystals. Here, b...

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Bibliographic Details
Published in:Nature communications 2020-05, Vol.11 (1), p.2483-2483, Article 2483
Main Authors: He, Yang, Li, Bin, Wang, Chongmin, Mao, Scott X.
Format: Article
Language:English
Subjects:
147/143
639/301/1023/1026
639/301/357/537
Boundaries
Crystal structure
Crystals
Deviation
Dislocations
Hexagonal close packed crystals
High resolution
Humanities and Social Sciences
Interfaces
Magnesium
MATERIALS SCIENCE
Metals and alloys
multidisciplinary
Nanocrystals
Nucleation
Rhenium
Science
Science (multidisciplinary)
structural properties
Titanium
Transmission electron microscopy
Twin boundaries
Twinning
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Summary:Design and processing of advanced lightweight structural alloys based on magnesium and titanium rely critically on a control over twinning that remains elusive to date and is dependent on an explicit understanding on the twinning nucleation mechanism in hexagonal close-packed (HCP) crystals. Here, by using in-situ high resolution transmission electron microscopy, we directly show a dual-step twinning nucleation mechanism in HCP rhenium nanocrystals. We find that nucleation of the predominant {1 0 −1 2} twinning is initiated by disconnections on the Prismatic│Basal interfaces which establish the lattice correspondence of the twin with a minor deviation from the ideal orientation. Subsequently, the minor deviation is corrected by the formation of coherent twin boundaries through rearrangement of the disconnections on the Prismatic│Basal interface; thereafter, the coherent twin boundaries propagate by twinning dislocations. The findings provide high-resolution direct evidence of the twinning nucleation mechanism in HCP crystals. Aspects of twinning in hexagonal-close-packed crystals remain elusive. Here, the authors directly image twinning in rhenium nanocrystals and show the process is mediated by disconnections on Prismatic│Basal interfaces as the twin initially deviates from its ideal orientation before it is corrected.
ISSN:2041-1723
2041-1723
DOI:10.1038/s41467-020-16351-0