中国物理B ›› 2009, Vol. 18 ›› Issue (10): 4370-4379.doi: 10.1088/1674-1056/18/10/046

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Three-dimensional size and orientation of the precipitates in AZ91 magnesium alloys measured by TEM techniques

郑鸥, 马家艳, 王建波, 周嘉萍, 金磊, 赵东山, 王仁卉   

  1. Department of Physics and Key Laboratory of Acoustic and Photonic Materials and Devices of Ministry of Education, Wuhan University, Wuhan 430072, China;Centre for Electron Microscopy, Wuhan University, Wuhan 430072, China
  • 收稿日期:2009-03-05 修回日期:2009-04-17 出版日期:2009-10-20 发布日期:2009-10-20
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant Nos 50571075 and 50771074) and the Program for New Century Excellent Talents in University, China (Grant No NCET-07-0640).

Three-dimensional size and orientation of the precipitates in AZ91 magnesium alloys measured by TEM techniques

Zheng Ou(郑鸥), Ma Jia-Yan(马家艳), Wang Jian-Bo(王建波)†, Zhou Jia-Ping(周嘉萍), Jin Lei(金磊), Zhao Dong-Shan (赵东山)‡, and Wang Ren-Hui(王仁卉)   

  1. Department of Physics and Key Laboratory of Acoustic and Photonic Materials and Devices of Ministry of Education, Wuhan University, Wuhan 430072, China;Centre for Electron Microscopy, Wuhan University, Wuhan 430072, China
  • Received:2009-03-05 Revised:2009-04-17 Online:2009-10-20 Published:2009-10-20
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant Nos 50571075 and 50771074) and the Program for New Century Excellent Talents in University, China (Grant No NCET-07-0640).

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摘要： Knowledge of the microscopic structure, including three-dimensional (3-D) size and orientation of the precipitates, is essential to fully understand the mechanical properties of the magnesium alloys and designing the alloys with better performance. Analytical TEM with high spatial resolution offers the simultaneous measurements of 3-D size, structure, orientation, composition of the precipitates from one typical sample along an established crystallographic axis. Besides popular Burgers orientation relationship (OR), other ORs such as Pitsch--Schrader OR, Crawley OR, Potter OR and a new OR with the form of [0001]α 1.0° from [311]γ and (11\bar 20)α 2.0° from (03\bar 3)γ between the magnesium matrix and the precipitate γ -Mg17Al12 are identified by TEM imaging and diffraction techniques. As a case study, the thicknesses of the individual precipitates with Burgers OR are further measured to be 100--200~nm through both electron energy-loss spectroscopy and x-ray energy dispersive spectroscopy combining differential x-ray absorption and extrapolation, which are in agreement with the overall 3-D size statistic distribution results obtained through analysing various samples along various directions. Furthermore, the fabricated wedge-shape structure provides a platform on which to study the dependence of the interfacial strain on the variation of the thickness.

Abstract: Knowledge of the microscopic structure, including three-dimensional (3-D) size and orientation of the precipitates, is essential to fully understand the mechanical properties of the magnesium alloys and designing the alloys with better performance. Analytical TEM with high spatial resolution offers the simultaneous measurements of 3-D size, structure, orientation, composition of the precipitates from one typical sample along an established crystallographic axis. Besides popular Burgers orientation relationship (OR), other ORs such as Pitsch--Schrader OR, Crawley OR, Potter OR and a new OR with the form of [0001]$\alpha$ 1.0° from [311]$\gamma$ and (11$\bar{2}$0)$\alpha$ 2.0° from (03$\bar{3}$)$\gamma$ between the magnesium matrix and the precipitate $\gamma$ -Mg17Al12 are identified by TEM imaging and diffraction techniques. As a case study, the thicknesses of the individual precipitates with Burgers OR are further measured to be 100--200 nm through both electron energy-loss spectroscopy and x-ray energy dispersive spectroscopy combining differential x-ray absorption and extrapolation, which are in agreement with the overall 3-D size statistic distribution results obtained through analysing various samples along various directions. Furthermore, the fabricated wedge-shape structure provides a platform on which to study the dependence of the interfacial strain on the variation of the thickness.

Key words: transmission electron microscopy, microstructure, Mg, electron energy loss spectroscopy

中图分类号:  (Alloys )

  • 61.66.Dk
61.05.jm (Convergent-beam electron diffraction, selected-area electron diffraction, nanodiffraction) 62.20.-x (Mechanical properties of solids) 68.37.Lp (Transmission electron microscopy (TEM)) 79.20.Uv (Electron energy loss spectroscopy) 81.20.Fw (Sol-gel processing, precipitation)