Influence of equal-channel angular pressing on aging precipitation in 7050 Al alloy

7050 Al alloy was successfully processed by equal-channel angular pressing (ECAP) at room temperature (RT). The effect of ECAP on the subsequent aging precipitation behavior was investigated by using transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM)....

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Bibliographic Details
Published in:Intermetallics 2014-12, Vol.55, p.49-55
Main Authors: Li, M.H., Yang, Y.Q., Feng, Z.Q., Feng, G.H., Huang, B., Chen, Y.X., Han, M., Ru, J.G.
Format: Article
Language:English
Subjects:
Aluminum base alloys
B. Precipitates
B. Strain-aging
C. Heat treatment
Deformation
Dislocations
Equal channel angular pressing
F. Electron microscopy, transmission
High density
Precipitation
Segregations
Vacancies
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Summary:7050 Al alloy was successfully processed by equal-channel angular pressing (ECAP) at room temperature (RT). The effect of ECAP on the subsequent aging precipitation behavior was investigated by using transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). The results reveal that the kinds, spatial distribution and sizes of precipitates in the unECAPed and the ECAPed samples are different. ECAP accelerates the process of aging precipitation and results in the broadening of precipitate size distribution. ECAP can produce not only deformation heat but also internal defects such as excess vacancies and high density of dislocations when the sample passes through the main deformation zone. Deformation heat can lead to pre-precipitation, forming a small amount of GPII zones during ECAP processing. Strain-induced excess vacancies make solute segregation along dislocations by the mechanism of nonequilibrium segregation. High density dislocations mainly accelerate the process of aging precipitation. Besides, dislocations also induce the competition between homogeneous precipitation and heterogeneous precipitation on dislocations due to the flow of solutes and vacancies towards dislocations. •Influence of ECAP on aging precipitation of 7050 Al alloy is studied.•ECAP generates significant heating and internal defects.•ECAP can accelerate the nucleation and growth of precipitate phases.•ECAP can result in a large precipitate size gradient.
ISSN:0966-9795
DOI:10.1016/j.intermet.2014.07.005