Article
Metallurgy & Metallurgical Engineering
Zhiwei Du, Yonggang Peng, Hang Teng, Zhong Cao, Kui Zhang, Minglong Ma, Xiaolei Han, Ting Li, Cong Che, Yongjun Li
Summary: Crystal structures, growth characteristics, and transformation of the precipitates in a Mg-7Gd-5Y-1Nd-2Zn-0.5Zr (wt.%) alloy aged at 200 degrees C were investigated. The study revealed the formation and development of solute clusters and various precipitates during aging, providing valuable insights into the aging behavior and performance of the alloy.
JOURNAL OF MAGNESIUM AND ALLOYS
(2023)
Article
Materials Science, Multidisciplinary
Zhenyang Liu, Bin Chen, Pengyu Zhao, Liping Yu, Zongrui Pei, Bijin Zhou, Yiqiang Hao, Nan Zhou, Xiaoqin Zeng
Summary: In this study, the atomic-scale characterization of precipitates in Mg-Gd-Y-Zn-Mn alloys was comprehensively examined. The observations revealed the formation and transformation processes of precipitates under different aging conditions. These findings provide valuable evidence for a better understanding of precipitates in Mg-Gd-Y-Zn-Mn alloys at the atomic level.
Article
Materials Science, Multidisciplinary
Z. H. Li, D. Cheng, K. Wang, E. R. Hoglund, J. M. Howe, B. C. Zhouc, T. T. Sasaki, T. Ohkubo, K. Hono
Summary: This study investigated the precipitation process of a Mg-0.3Ca-0.6Zn alloy during isothermal aging at 200 degrees C using advanced microscopy techniques and first-principles calculations. The results revealed the formation of monolayer G.P. zones, which transformed into tri-atomic layer η'' and η' plates. The η' plates then formed pairs and stacks with pure magnesium layers. The unique structure of coarse η1 plates led to a different precipitate microstructure evolution from other Mg-RE-Zn alloys. First-principles calculations confirmed the crystal structure and stability of the precipitates, supporting a new precipitation sequence.
Article
Materials Science, Multidisciplinary
Lipeng Ding, Yaoyao Weng, Zhihong Jia, Ruojin Zang, Kaiyun Xiang, Qing Liu, Hiromi Nagaum
Summary: The evolution mechanism of multiple metastable precipitates in Si-rich Al-Mg-Si alloy was studied using high resolution microscopy and first-principles calculation. It was found that the beta'' phase transforms simultaneously to various types of precipitates in the over-aged stage, with two different evolution paths proposed. The formation and evolution of substructures are key factors in the transformation of precipitates.
PHILOSOPHICAL MAGAZINE
(2022)
Article
Materials Science, Multidisciplinary
M. F. Chisholm, D. Shin, G. Duscher, M. P. Oxley, L. F. Allard, J. D. Poplawsky, A. Shyam
Summary: This study accurately determines the atomic structure of semi-coherent precipitate interfaces using aberration-corrected scanning transmission electron microscopy and first-principles calculations, revealing critical features that determine the thermal stability of precipitation-hardened alloys.Unexpected misfit dislocations are found to be key in accommodating the misfit between the matrix and strengthening phase.
Article
Materials Science, Multidisciplinary
S. L. Yang, X. J. Zhao, H. W. Chen, N. Wilson, J. F. Nie
Summary: The precipitates in an aged Al-Cu-Mg-Ag alloy were characterized using atomic-resolution EDXS STEM and HAADF STEM. A metastable precursor phase, Omega', with a hexagonal structure and a thickness of 0.915 nm, was found. The presence of Omega' reduces the energy barrier for the nucleation of Omega.
Article
Chemistry, Physical
B. Z. Sun, X. L. Lu, Q. Y. Huang, L. R. Liu
Summary: In this study, the formation mechanism of beta(1) precipitate in precipitation-hardenable rare earth magnesium alloys is investigated. The phase transformation from beta(s)' to beta(1) is examined using atomic-scale high-angle annular dark-field scanning transmission electron microscopy, and the nucleation and growth mechanisms of beta(1) are proposed. The results reveal the occurrence of pseud beta(1) with a lower Ce-content on the domain boundary between two sets of staggered beta(')(S) lattices, and the structural evolution from beta(')(S) to beta(1) is implemented layer by layer through pseud beta(1). Nucleation and growth pathways are discussed based on the formation energy and strain energy.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Nanoscience & Nanotechnology
B. Z. Sun, Y. Dong, J. Tan, Y. Tian, J. X. Ren
Summary: The study investigates a novel basal plate designated as gamma''' in a Mg-Nd-Ca alloy, revealing its hexagonal structure, ternary composition, and extraordinary origin derived from a Mg2Ca C14 Laves phase. This research contributes to a new understanding of the formation mechanism of gamma-type basal precipitates.
SCRIPTA MATERIALIA
(2021)
Article
Chemistry, Physical
Tsai-Fu Chung, Shan-Qiao Lin, Hongxing Li, Chien-Nan Hsiao, Jer-Ren Yang, Cheng-Si Tsao, Takahito Ohmura
Summary: We present a study on the microstructure evolution and strengthening behavior of delta'/theta'/delta' precipitates in the aged Al-Cu-Li-Mg aluminum alloy using atomic high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and in-situ TEM compression straining. The in-situ microstructure evolution of the delta'/theta'/delta' precipitates is observed through atomic HAADF-STEM images. The formation of a monolayer GP(theta') zone, grown on the (001)(Al) plane, and subsequent transformation to theta' phase leads to the maturity of delta'/theta'/delta' precipitates. Dislocation-precipitate interactions, as well as the effects of inclined boundaries and thin T-1 precipitates, are investigated during in-situ TEM compression straining. The presence of stacking fault layers within sheared delta'/theta'/delta' precipitates is revealed by atomic HAADF-STEM images. Copyright © 2023 Elsevier B.V. All rights reserved.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Multidisciplinary Sciences
Hwangsun Kim, Howook Choi, Juhyun Oh, Sangmin Lee, Ho Kwon, Eun Soo Park, Sungwoo Lee, Gun -Do Lee, Miyoung Kim, Heung Nam Han
Summary: In this study, the interfacial structure of ri4 precipitates in Al-Zn-Mg alloys is revealed, showing pseudo-periodic steps and bridges. This peculiar interface structure stabilizes the ri4 precipitates by relieving the strain energy. The results provide insights into the nucleation and growth of precipitates and offer a pathway for tailoring the mechanical properties of alloys by controlling their precipitation kinetics.
Article
Chemistry, Physical
B. Li, T. Shen, B. Z. Sun
Summary: In this study, the early precipitation products of an aged Mg- 3.0 wt%Ce alloy were investigated using aberration-corrected HAADF-STEM. Two novel Ce-rich ordered structures, namely 6 H and 18R-type superstructures, were identified.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Metallurgy & Metallurgical Engineering
B. Z. Sun, H. X. Zhang, Y. Dong, J. X. Ren, Y. Tian, G. M. Xie, J. Tan, Y. H. Sun, Na Xiao
Summary: The structural evolution from beta(1) (Mg3Ce) to beta (Mg12Ce) precipitates in binary Mg-Ce alloys was investigated using high-angle annular dark-field scanning transmission electron microscopy, revealing a transformation mainly in {111} beta 1 crystallographic planes. The newly formed beta lattices exhibit rotational and translational domains, contributing to enhanced hardness and strength in the alloy.
JOURNAL OF MAGNESIUM AND ALLOYS
(2021)
Article
Metallurgy & Metallurgical Engineering
Q. Q. Jin, X. H. Shao, Y. T. Zhou, B. Zhang, S. J. Zheng, X. L. Ma
Summary: The formation of beta' phase in an Mg88Co5Y7 alloy after aging or electron beam irradiation has been studied using high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). It was found that beta' phase precipitated only in the Mg matrix and not in the LPSO structures after aging. However, the LPSO structures with stacking defects transformed into the beta'-long phase during electron beam irradiation.
JOURNAL OF MAGNESIUM AND ALLOYS
(2022)
Article
Chemistry, Physical
Yang Zhao, Jingxu Zheng, Xiaodong Wang, Xiaoqin Zeng, Bin Chen
Summary: This study provides a comprehensive investigation of LPSO structures and precipitates in Mg-Gd-Y-Cu alloy during aging treatment, revealing the evolution of various structures in the alloy and identifying the formation of novel Gd3Y precipitates for the first time. The composite strengthening effect of LPSO, beta', and Gd3Y precipitates significantly contributes to the strengthening effect on the alloy.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Chemistry, Multidisciplinary
Benzhe Sun, Jingxin Ren, Jing Wang, Xinglong Lv, Yanzhao Zeng, Jinshan Chen
Summary: The shapes and orientations of precipitates significantly affect the mechanical properties of precipitation-strengthened magnesium alloys. This study examines the microstructure and precipitation behaviors of an aged Mg-3.0 wt % La alloy using atomic resolution scanning transmission electron microscopy. The main precipitate at the peak-aged stage is a face-centered cubic (FCC) La-enriched solid solution, which evolves into a tetragonal (T) lattice precipitation strengthening phase at the over-aged stage. The crystallographic orientations and shapes of FCC and T precipitates are elaborated on.
CRYSTAL GROWTH & DESIGN
(2023)
