Cluster hardening in Al-3Mg triggered by small Cu additions. (December 2018)

• Record Type: Journal Article
• Authors: Medrano, S.; Zhao, H.; De Geuser, F.; Gault, B.; Stephenson, L.T.; Deschamps, A.; Ponge, D.; Raabe, D.; Sinclair, C.W.
• Is Part Of: Acta materialia. Volume 161(2018)
• Page Start: 12
• Page End: 20
• Publication Date: 2018-12
• Subjects: Precipitation -- Aluminum alloys -- Yield strength -- Atom probe; Materials -- Periodicals; Materials science -- Periodicals; Materials -- Mechanical properties -- Periodicals; Metallurgy -- Periodicals; Chemistry, Inorganic -- Periodicals; 620.112
• DOI: 10.1016/j.actamat.2018.08.050
• Languages: English
• ISSNs: 1359-6454

Abstract

Abstract: The aging response of two Al-3Mg alloys with Cu addition < 1 wt% has been tracked under simulated automotive paint bake conditions ( ∼ 20 min, 160 and 200 °C) to quantify the processes controlling hardening. The decomposition of the solid solution, observed by atom probe tomography, has been interpreted using a novel pair correlation function approach and incorporated into a model for prediction of precipitation hardening. It is shown that the hardening is controlled by clusters/Guinier-Preston-Bagaryatsky (GPB) zones similarly to what has been previously observed in much higher Cu containing 2XXX-series alloys. Interestingly, it is shown that very small additions of Cu ( < 0.1 at%) can be used to catalyze a high number density of strengthening particles owing to the high enrichment in Mg compared to particles found in more conventional high Cu/low Mg alloys. This allows hardening during the first hour of aging that is as high as that obtainable in these high Cu alloys. Graphical abstract: Image 1