TEM Observation of Metastable Phases in Aged Al-Mg-Ge Alloys

Abstract:

The purpose of study is to investigate aging behavior, crystal structures of metastable phase and relative frequency of metastable phases in aged Al-Mg-Ge and Al-Mg-Ge-Si alloys using high resolution transmission electron microscope (HRTEM), energy dispersive X-ray spectroscopy (EDS) and electron energy-loss spectroscopy (EELS). Every alloy included rod-shaped precipitate which is the same as the typical metastable pahse, ’, in Al-Mg-Si alloy. Except to Mg-rich alloys, the Type-A precipitate, which is a typical metastable phase in the excess Si type Al-Mg-Si alloys and popular at over aged condition, was confirmed as a large rod-shaped precipitates in those alloys. This behavior is probably depends on the ratio of Mg/Ge. Also, Mg, Si and Ge were detected from the ’-phase in Al-Mg-Ge-Si alloy by EELS. This means that the ’-phase in Al-Mg-Ge-Si alloy consists of these 3 elements including Si, not just Ge to form metastable Mg2Ge.

• Periodical: Materials Science Forum (Volumes 654-656)
• Pages: 930-933
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.654-656.930
• Online since: June 2010
• Authors: Kenji Matsuda, Junya Nakamura, Keisuke Yamamoto, Tokimasa Kawabata, Yasuhiro Uetani, Susumu Ikeno
• Keywords: Al-Mg-Ge Alloy, EDS, Elemental Map, HRTEM, Metastable Phase, Precipitation

References

[1] A. Lutts: Acta Met. Vol. 9 (1961), p.577.

[2] K. Matsuda, T. Munekata, T. Kawabata, Y. Uetani and S. Ikeno: J. Japan Inst. Light Metals, Vol. 56 (2006), p.680.

[3] K. Matsuda, S. Ikeno, H. Matsui, T. Sato, K. Terayama and Y. Uetani: Met. Mater. Trans. Vol. 36A (2005), p. (2007).

[4] G. Cliff and G. W. Lorimer: J. Micros, Vol. 103 (1975), p.203.