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

Lin Jiang; Mingyu Gong; Jian Wang; Zhiliang Pan; Xin Wang; Dalong Zhang; Y Morris Wang; Jim Ciston; Andrew M Minor; Mingjie Xu; Xiaoqing Pan; Timothy J Rupert; Subhash Mahajan; Enrique J Lavernia; Irene J Beyerlein; Julie M Schoenung

doi:10.1038/s41467-021-27591-z

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

Nat Commun. 2022 Jan 10;13(1):20. doi: 10.1038/s41467-021-27591-z.

Authors

Lin Jiang^{1

2}, Mingyu Gong³, Jian Wang⁴, Zhiliang Pan¹, Xin Wang¹, Dalong Zhang¹, Y Morris Wang⁵, Jim Ciston⁶, Andrew M Minor^{6

7}, Mingjie Xu¹, Xiaoqing Pan^{1

8}, Timothy J Rupert¹, Subhash Mahajan⁹, Enrique J Lavernia¹⁰, Irene J Beyerlein¹¹, Julie M Schoenung¹²

Affiliations

¹ Department of Materials Science and Engineering, University of California, Irvine, CA, 92697, USA.
² Materials & Structural Analysis Division, Thermo Fisher Scientific, Hillsboro, OR, 97124, USA.
³ State Key Lab of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai, 200240, China.
⁴ Department of Mechanical & Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE, 68588, USA.
⁵ Department of Materials Science and Engineering, University of California, Los Angeles, Los Angeles, CA, 90095, USA.
⁶ Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94701, USA.
⁷ Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA.
⁸ Department of Physics and Astronomy, University of California, Irvine, CA, 92697, USA.
⁹ Department of Materials Science and Engineering, University of California, Davis, CA, 95616, USA.
¹⁰ National Academy of Engineering, Irvine, CA, 92617, USA.
¹¹ Department of Mechanical Engineering and Materials, University of California, Santa Barbara, CA, 93101, USA.
¹² Department of Materials Science and Engineering, University of California, Irvine, CA, 92697, USA. schoenuj@uci.edu.

Abstract

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.