Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1575812 | Materials Science and Engineering: A | 2013 | 10 Pages |
Abstract
During ageing at 200 °C, a trace (0.2 wt%) addition of Ge to a base Al-3.5Cu-0.4Mg alloy resulted in anomalous precipitation processes by stimulating the formation of nanoscale precipitate and suppressing the formation of Sâ²(Al2CuMg) precipitate. This behavior was demonstrated to be closely related to the preferential Mg-Ge cluster which formed in the early ageing stage. The increased hardening response and enhanced hardness in Ge-containing alloy were due to the rapid precipitation of high density of fine nanoscale precipitate. The transmission electron microscopy (TEM) investigation indicated that nanoscale precipitate, θⲠ(Al2Cu), θâ²II (Al2Cu) and Ï (Al5Cu6Mg2) precipitates could coexist in Al matrix for prolonged ageing at 200 °C. And the nanoscale precipitate was demonstrated to own ã001ãα needle-shaped morphology and be enriched with aluminum, copper, magnesium and germanium. The Mg/(Cu+Ge) atomic ratio in them is close to 1:1. High-resolution TEM observation indicated that the nanoscale precipitates appeared to be coherent with Al matrix and their orientation relationship is ã100ãnano//ã100ãAl and {010}nano//{010}Al. A modified structure with composition of Al10Mg3Cu3âxGex (0
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Authors
Z.Q. Liao, Z.Q. Zheng, S.C. Li, W.Q. Liu, B. Cai, S. Zhong,