influence of deformation by equal-channel angular pressing on the ageing response and precipitate fracturing: case of the Al–Ag alloy

Severe plastic deformation (SPD) processes reduce drastically the grain size of metals, leading to a substantial increase of mechanical strength. Additionally, it has been observed that the precipitation kinetics in some Al alloys is accelerated after SPD, and thus suitable heat treatments can be us...

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Bibliographic Details
Published in:Journal of materials science 2015-01, Vol.50 (1), p.138-143
Main Authors: Sordi, Vitor L, Feliciano, Carlos A, Ferrante, Maurizio
Format: Article
Language:English
Subjects:
Aging (metallurgy)
Alloys
aluminum
Aluminum base alloys
Analysis
Characterization and Evaluation of Materials
chemical precipitation
Chemistry and Materials Science
Classical Mechanics
Crystallography and Scattering Methods
Deformation
Dislocations
Equal channel angular pressing
Fracturing
Grain size
heat treatment
kinetics
Materials Science
microstructure
Original Paper
Ostwald ripening
Plastic deformation
Polymer Sciences
Precipitates
Precipitation
Precipitation (Meteorology)
pressing
silver
Silver base alloys
Solid Mechanics
Specialty metals industry
Substructures
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Summary:Severe plastic deformation (SPD) processes reduce drastically the grain size of metals, leading to a substantial increase of mechanical strength. Additionally, it has been observed that the precipitation kinetics in some Al alloys is accelerated after SPD, and thus suitable heat treatments can be used as a strategy for further hardening. In this work an Al–17 % Ag alloy was processed by equal-channel angular pressing (ECAP) and aged at 400 °C for different lengths of time with the purpose of observing and quantifying the kinetics of precipitation and competitive growth of the Al₂Ag phase, as well as the precipitate fracturing and dissolution by ECAP. Microstructure observation of samples aged before ECAP deformation showed that precipitate bending rather than fracturing was the dominant event. The Al₂Ag plates precipitation kinetics were studied on samples aged in the coarse-grained condition and after ECAP; results show that in the former group of samples the kinetics is well described by the Ham, Horvay and Cahn analysis. In the ECAP processed samples, a much faster than expected Ostwald ripening type of growth was observed. Such behaviour was attributed to a dislocation substructure stabilized by the Al₂Ag precipitates.
ISSN:0022-2461
1573-4803
DOI:10.1007/s10853-014-8573-9