Stacking Faults and Growth Twins in Long‐Period Stacking‐Ordered Structures in Mg–Co–Y Alloys. Issue 4 (12th December 2019)

• Record Type: Journal Article
• Authors: Jin, Qianqian; Shao, Xiaohong; Peng, Zhenzhen; Zhou, Yangtao; Zhang, Bo; Zheng, Shijian; Ma, Xiuliang
• Is Part Of: Advanced engineering materials. Volume 22:Issue 4(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2019-12-12
• Subjects: high-angle annular dark-field scanning transmission electron microscopy -- long-period stacking-ordered structure -- magnesium alloys -- stacking faults; Materials -- Periodicals; 620.11
• DOI: 10.1002/adem.201901029
• Languages: English
• ISSNs: 1438-1656

Abstract

Abstract : Herein, by atomic‐scale high‐angle annular dark field scanning transmission electron microscopy, the structure, symmetry, and distribution of stacking faults (SFs) and growth twins in 12H, 15R, and 18R long‐period stacking‐ordered (LPSO) structures in Mg88 Co5 Y7 and Mg92 Co2 Y6 (at%) as‐cast alloys are characterized. The SFs or growth twins in LPSO structures are denoted as the faulted arrangement of n ‐Mg components, and some of them possess inversion centers or mirror symmetry. The formation of SFs or growth twins in 15R and 18R structures depends on whether the sum of Mg layers in all the n ‐Mg components of the defect is an even number or an odd number, whereas only SFs form in 12H structures. Various types of SFs or SFs of the same kind can distribute locally in the LPSO structures in Mg–Co–Y alloys, and then some other LPSO structures with a longer period are detected via orderly distribution of SFs. Abstract : The structure, symmetry, and distribution of stacking faults (SFs) and growth twins are characterized in LPSO structures in Mg alloys. Atomic‐scale scanning transmission electron microscopy (STEM) unravels that the formation of SFs and growth twins in LPSO structures depends on even number or odd number of Mg layers in all the n ‐Mg components.