Twinning and antitwinning in body-centered cubic metals

0563134 - ÚFM 2024 RIV NL eng J - Journal Article
Gröger, Roman - Holzer, Jakub - Kruml, Tomáš
Twinning and antitwinning in body-centered cubic metals.
Computational Materials Science. Roč. 216, JAN (2023), č. článku 111874. ISSN 0927-0256. E-ISSN 1879-0801
R&D Projects: GA ČR(CZ) GA19-23411S
Research Infrastructure: CzechNanoLab - 90110
Institutional support: RVO:68081723
Keywords : TwinningAntitwinningBCC metalsComputer simulationDiffraction * Antitwinning * BCC metals * Computer simulation * Diffraction
OECD category: Condensed matter physics (including formerly solid state physics, supercond.)
Impact factor: 3.3, year: 2022
Method of publishing: Limited access
https://www.sciencedirect.com/science/article/pii/S0927025622005857?via%3Dihub

Deformation twinning in body-centered cubic (BCC) metals occurs by shearing the crystal along planes parallel to directions. One of these directions (twinning shear) produces a twin, but it is often argued that the opposite sense of shearing (antitwinning shear) does not lead to twin formation. However, recent slip trace and orientational mapping analyses made on many BCC metals after low-temperature plastic deformation show clear evidence of fine misoriented lamellae along the traces of {112} planes sheared in the antitwinning sense. To resolve this controversy, we have utilized molecular statics simulations to determine the energy barriers for uniformly shearing all transition and alkali BCC metals in the twinning and antitwinning sense. The results of these simulations show that twins in transition BCC metals of the 5th and 6th groups can be produced on both types of {112} planes, irrespective of whether the shear is applied in the twinning or the antitwinning sense. However, this is not the case for -Fe and the BCC structures of the alkali metals Li, Na, and K, where twins are likely to occur only on {112} planes sheared in the twinning sense. Furthermore, we have used TEM diffraction pattern analyses to investigate the characters of misoriented deformation lamellae in Nb and Cr compressed at 77 K, which were found along {112} planes sheared in the antitwinning sense. We demonstrate that these regions constitute regular twins. Similar studies on -Fe compressed at 77 K prove that twinning in this material takes place exclusively on {112} planes sheared in the twinning sense.
Permanent Link: https://hdl.handle.net/11104/0341694