Precipitation structure and mechanical properties on peak-aged Al-Zn-Mg alloys including different with some zn/mg ratios

Seungwon Lee, Katsumi Watanabe, Kenji Matsuda, Katsuhiko Nishimura, Norio Numomura, Hiroyuki Toda, Kyosuke Hirayama, Kazuyuki Shimizu, Hongye Gao, Masatake Yamaguchi, Kenichi Ebihara, Mitsuhiro Itakura, Tomohito Tsuru, Tomoo Yoshida, Satoshi Murakami, Susumu Ikeno

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2 Citations (Scopus)

Abstract

Al-Zn-Mg alloys with different ratios of Zn/Mg have been investigated to understand the influence of the Zn/Mg ratios on age-hardening, microstructures and precipitates. Alloys containing higher ratios of Zn to Mg revealed higher peak hardness, ultimate tensile strengths, 0.2% proof stresses and higher number densities of precipitates per unit area. A square shaped T'-phase has been observed in the matrices of low Zn/Mg ratio alloys aged at 423 K with the aid of transmission electron microscope (TEM) images and its selected area electron diffraction (SAED) patterns, while SAED patterns of η and/or η-phase have been detected in high Zn/Mg ratio alloys. When aging temperature is lowered to 393 K, η'/η-phase have been again observed in the matrix, though no T'-phase was detected in low Zn/Mg ratio alloys. The aging condition in the present work has turned out to be on over aged condition for low Zn/Mg ratio alloys with coarse precipitates of T'-phase in the matrix, because those alloys attained lower peak hardness, tensile strength and higher elongation than high Zn/Mg ratio alloys which have fine η '/η-phase.

Original languageEnglish
Pages (from-to)162-167
Number of pages6
JournalKeikinzoku/Journal of Japan Institute of Light Metals
Volume67
Issue number5
DOIs
Publication statusPublished - Jan 1 2017

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All Science Journal Classification (ASJC) codes

  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry

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