Abstract
Twinning, on par with dislocations, is critically required in plastic deformation of hexagonal close-packed crystals at low temperatures. In contrast to that in cubic-structured crystals, twinning in hexagonal close-packed crystals requires atomic shuffles in addition to shear. Though the twinning shear that is carried by twinning dislocations has been captured for decades, direct experimental observation of the atomic shuffles, especially when the shuffling mode is not unique and does not confine to the plane of shear, remains a formidable challenge to date. Here, by using in-situ transmission electron microscopy, we directly capture the atomic mechanism of the 112¯1 twinning in hexagonal close packed rhenium nanocrystals. Results show that the 112¯1 twinning is dominated by the (b1/2, h1/2) twinning disconnections. In contrast to conventional expectations, the atomic shuffles accompanying the twinning disconnections proceed on alternative basal planes along 1/6 11¯00, which may be attributed to the free surface in nanocrystal samples, leading to a lack of mirror symmetry across the 112¯1 twin boundary.
| Original language | English |
|---|---|
| Article number | 2994 |
| Journal | Nature Communications |
| Volume | 15 |
| Issue number | 1 |
| DOIs | |
| State | Published - Dec 2024 |
| Externally published | Yes |
Funding
S.X.M. acknowledges support from the National Science Foundation (NSF CMMI 1808046 and CMMI-1760916) through the University of Pittsburgh. C.M.W. was supported by the PNNL LDRD program. This work was performed, in part, at the William R. Wiley Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the U.S. Department of Energy, Office of Biological and Environmental Research, and located at PNNL. PNNL is operated by Battelle for the U.S. Department of Energy under contract DE-AC05-76RLO1830. The authors would like to thank Dr. Bin Li from the University of Nevada Reno for valuable discussions.