Nucleation of precipitates in aged Al-Cu-Mg-(Ag) alloys with high Cu:Mg ratios

Journal Article · Wed May 01 04:00:00 EDT 1996 · Acta Materialia

DOI:https://doi.org/10.1016/1359-6454(95)00314-2· OSTI ID:247944

Ringer, S P; Hono, K; Sakurai, T ^[1]; Polmear, I J ^[2]

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1. Tohoku Univ., Sendai (Japan). Inst. for Materials Research
2. Monash Univ., Clayton (Australia). Dept. of Materials Engineering

Clustering and precipitation reactions during the early stages of ageing at 180 C in an Al-1.7Cu-0.3Mg (at.%) alloy and equivalent alloys containing 0.1 and 0.2 at.% Ag have been studied. Transmission electron microscopy, electron diffraction and atom probe field ion microscopy have been used to clarify the precipitation processes in these alloys following ageing for 15, 30, 120, 720 and 9,000 s. Reactions involving the formation of Mg and Mg-Cu co-clusters were observed in the ternary Al-Cu-Mg alloy whereas Mg, Ag and Mg-Ag co-clusters were found to co-exist with Cu-clusters in the quaternary Al-Cu-Mg-Ag alloy. Results indicate that the Mg-Ag interaction is strong and it is proposed that the role of Ag in quaternary alloys is to effectively trap Mg atoms, resulting in Mg-Ag co-clusters, which provide favorable sites for nucleation of the {Omega} phase. Various models for precursor phases have also been examined. Apart from the presence of Mg-Ag co-clusters, no evidence of a distinct precursor phase was observed.

• OSTI ID: 247944
• Journal Information: Acta Materialia, Journal Name: Acta Materialia Journal Issue: 5 Vol. 44; ISSN XZ504Y; ISSN 1359-6454
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
AGING
ALUMINIUM ALLOYS
COPPER ALLOYS
ELECTRON DIFFRACTION
ION MICROSCOPY
MAGNESIUM ADDITIONS
MATHEMATICAL MODELS
MICROSTRUCTURE
PHASE STUDIES
PRECIPITATION
SILVER ADDITIONS
STRAINS
TIME DEPENDENCE
TRANSMISSION ELECTRON MICROSCOPY