Influence of treatment pathways on the precipitation behaviors of Al-Mg-Si-Cu-(Zn)-Mn alloys

• Published in: Journal of alloys and compounds Vol. 797; pp. 26 - 38
• Main Authors: Yuan, Bo, Guo, Mingxing, Wu, Yuan, Zhang, Jishan, Zhuang, Linzhong, Lavernia, Enrique J.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 15.08.2019; Elsevier BV
• Subjects: Age hardening; Aging (artificial); Aging (metallurgy); Al-Mg-Si-Cu-Zn-Mn alloy; Alloy systems; Alloys; Aluminum base alloys; Copper; Kinetics; Magnesium compounds; Mechanical properties; Metal silicides; Microstructure; Nucleation; Precipitates; Precipitation behavior; Precipitation hardening; Silicon; Zinc; Mechanical properties; Precipitation behavior; Kinetics; Microstructure; Al-Mg-Si-Cu-Zn-Mn alloy
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2019.05.055

We report on a systematic study of the influence of three different treatment pathways on the precipitation behavior of Al-Mg-Si-Cu-(Zn)-Mn alloys involving microstructure characterization, property measurements and modelling. The results reveal that the formation of coarse Mg2Si and Si particles in a Al-Mg-Si-Cu-Mn alloy during annealing at 400 °C can be avoided by adding Zn; the latter can improve the nucleation of precipitates, and increase the number density of β″ precipitates in the Al-Mg-Si-Cu alloy in both the non-isothermal and isothermal peak aging states, corresponding to a decrease in the activation energies of precipitation calculated on the basis of a modified AJM kinetics model, and finally resulting in an enhanced age hardening response in Al-Mg-Si-Cu-Zn-Mn. Moreover, although β″, Q′ and β′ precipitates with structures similar to those of Al-Mg-Si-Cu-Mn alloys, and an absence of Mg-Zn precipitates were observed in the Zn-containing Al-Mg-Si-Cu-Mn alloy after different treatment pathways, the incorporation of Zn atoms in the precipitates formed in the Zn-containing alloy was confirmed using APT characterization and the changes in the lattice parameter. [Display omitted] •Treatment pathways greatly affect the precipitation behaviors of Al alloys.•Zn addition could avoid the formation of coarse Mg2Si and Si particles.•Mg-Zn precipitates were not observed in the Zn-added alloy.•The incorporation of Zn atoms in the precipitates was confirmed.