Visualization and validation of twin nucleation and early-stage growth in magnesium

• Published in: Nature communications Vol. 13; no. 1; pp. 20 - 11
• Main Authors: Jiang, Lin, Gong, Mingyu, Wang, Jian, Pan, Zhiliang, Wang, Xin, Zhang, Dalong, Wang, Y. Morris, Ciston, Jim, Minor, Andrew M., Xu, Mingjie, Pan, Xiaoqing, Rupert, Timothy J., Mahajan, Subhash, Lavernia, Enrique J., Beyerlein, Irene J., Schoenung, Julie M.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 10.01.2022; Nature Publishing Group; Nature Portfolio
• Subjects: 147/137; 147/143; 639/301/1023/1026; 639/301/1034/1035; 639/301/1034/1037; 639/301/357/537; Atomistic models; Computational methods; Crystal growth; Crystals; Deformation; Design; Engineering; Flow stability; Geometry; Humanities and Social Sciences; Magnesium; MATERIALS SCIENCE; Metals; Metals and alloys; multidisciplinary; Nucleation; Propagation; Science; Science (multidisciplinary); Simulation; Stress concentration; Structural properties; Transmission electron microscopy; Twinning; Visualization
• DOI: 10.1038/s41467-021-27591-z
• ISSN: 2041-1723

The abrupt occurrence of twinning when Mg is deformed leads to a highly anisotropic response, making it too unreliable for structural use and too unpredictable for observation. Here, we describe an in-situ transmission electron microscopy experiment on Mg crystals with strategically designed geometries for visualization of a long-proposed but unverified twinning mechanism. Combining with atomistic simulations and topological analysis, we conclude that twin nucleation occurs through a pure-shuffle mechanism that requires prismatic-basal transformations. Also, we verified a crystal geometry dependent twin growth mechanism, that is the early-stage growth associated with instability of plasticity flow, which can be dominated either by slower movement of prismatic-basal boundary steps, or by faster glide-shuffle along the twinning plane. The fundamental understanding of twinning provides a pathway to understand deformation from a scientific standpoint and the microstructure design principles to engineer metals with enhanced behavior from a technological standpoint. The origins of deformation twins in Mg have remained unclear in the past. Here the authors, by combining in situ experimental observations and atomistic simulations, capture the rapid twinning phenomena in Mg crystals and show that twinning occurs through pure atomic shuffle.