Twin Boundary Superstructures Assembled by Periodic Segregation of Solute Atoms

• Published in: Nano letters 2021-11, Vol.21 (22), p.9642-9650
• Main Authors: Xie, Hongbo, Pan, Hucheng, Bai, Junyuan, Xie, Dongsheng, Yang, Peijun, Li, Shanshan, Jin, Jianfeng, Huang, Qiuyan, Ren, Yuping, Qin, Gaowu
• Format: Article
• Language: English
• Subjects: Alloys - chemistry
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/acs.nanolett.1c03448

Twinning is a common deformation mechanism in metals, and twin boundary (TB) segregation of impurities/solutes plays an important role in the performances of alloys such as thermostability, mobility, and even strengthening. The occurrence of such segregation phenomena is generally believed as a one-layer coverage of solutes alternately distributed at extension/compression sites, in an orderly, continuous manner. However, in the Mn-free and Mn-containing Mg–Nd model systems, we reported unexpected three- and five-layered discontinuous segregation patterns of the coherent {101̅1} TBs, and not all the extension sites occupied by solutes larger in size than Mg, and even some larger sized solutes taking the compression sites. Nd/Mn solutes selectively segregate at substitutional sites and thus to generate two new types of ordered two-dimensional TB superstructures or complexions. These findings refresh the understanding of solute segregation in the perfect coherent TBs and provide a meaningful theoretical guidance for designing materials via targeted TB segregation.