Al-Zn-Mg 系発泡体の材料強度と析出挙動に及ぼす熱処理の影響 / Effect of Heat Treatments on Matrix Strength and Precipitation Behavior in Al-Zn-Mg Foams
- Resource Type
- Journal Article
- Authors
- Koichi Makii; Seiji Nishi; Yasuhiro Aruga; 有賀 康博; 槙井 浩一; 西 誠治
- Source
- 日本金属学会誌 / Journal of the Japan Institute of Metals and Materials. 2009, 73(8):630
- Subject
- Guinier-Preston zone (GP zone)
X-ray absorption fine structure (XAFS)
aluminum foam
heat treatment
precipitation
transmission electron microscopy (TEM)
- Language
- Japanese
- ISSN
- 0021-4876
1880-6880
Al-Zn-Mg foams manufactured by a batch casting process were subjected to aging treatments with and without solution treatment. The effect of the heat treatments on matrix strength (micro-hardness) and precipitation behavior in the foams was investigated by means of transmission electron microscopy (TEM) and X-ray absorption fine structure (XAFS) analysis at a synchrotron radiation facility. Foam aged at 398 K for 8 h after the solution treatment showed the greatest increase in strength. Fine precipitates were dispersed homogeneously and densely, which were speculated to be metastable η′ and equilibrium η phases transformed from GP zones. It is estimated that the GP zones were formed during water-quenching after the solution treatment. Overaging treatment at 423 K for 48 h after solution treatment softened the foam past its peak strength by approximately 10 in Vickers hardness. During this treatment, η′ and η phases coarsened significantly and the number density of these precipitates decreased. It is concluded that a significant drop in the strength was suppressed during overaging by the presence of a high density of the GP zones, defined as Zn-Mg ordered phases by the XAFS analysis.