Guinier-Preston zones observed by high-angle annular detector dark-field scanning transmission electron microscopy

Toyohiko J. Konno, Masahiro Kawasaki, Kenji Hiraga

Research output: Contribution to journalArticlepeer-review

27 Citations (Scopus)

Abstract

We have examined Guinier-Preston (GP) zones in aged Al-Cu alloys using atomic-resolution high-angle annular detector dark-field (HAADF) scanning transmission electron microscopy (STEM), together with conventional high-resolution transmission electron microscopy (HRTEM). Because the imaging of coherent Cu precipitates in an Al matrix by HAADF-STEM is less sensitive to the imaging conditions that would severely limit HRTEM, densely populated GP-I zones are clearly observed. From the HAADF-STEM observations, we have found the GP-I zones to consist of two Cu layers, in addition to the commonly known monolayered GP-I zones. The structure of GP-II zones, in which Cu monolayers are separated by three Al layers, was identified, whereas a variant of GP-II zones does exist, for example double Cu layers separated by a single Al layer. In addition, in the GP-I stage, we have occasionally found Cu monolayers separated by three Al layers, which can be the incipient stage of GP-II zones. These results are in general agreement with previous observations by small-angle scattering and field ion microscopy. Also, our results indicate that the GP-II zone can act as a nucleation site for the θ′ phase.

Original languageEnglish
Pages (from-to)1713-1724
Number of pages12
JournalPhilosophical Magazine B: Physics of Condensed Matter; Statistical Mechanics, Electronic, Optical and Magnetic Properties
Volume81
Issue number11
DOIs
Publication statusPublished - 2001

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Physics and Astronomy(all)

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