Precipitation behaviour in AlMgZnCuAg crossover alloy with coarse and ultrafine grains

Abstract

Crossover aluminium alloys have recently been introduced as a new class of coarse-grained age-hardenable alloys. Here, we study the evolution of precipitation of the T-phase — ${\mathrm{M}\mathrm{g}}_{32}(\mathrm{Z}\mathrm{n},\mathrm{A}\mathrm{l}{)}_{49}$-phase — in a 5xxx/7xxx crossover alloy with coarse- and ultrafined microstructures. Both alloys were examined using differential scanning calorimetry, X-ray diffraction and in situ transmission electron microscopy. The ultrafine-grained alloy revealed significant different and accelerated precipitation behaviour due to grain boundaries acting as fast diffusion paths. Additionally, the ultrafine-grained alloy revealed high resistance to grain growth upon heating, an effect primarily attributed to inter-granular precipitation synergistically with trans-granular precipitation of T-phase.

GRAPHICAL ABSTRACT

IMPACT STATEMENT

The effect of coarse and ultrafine grains on the T-phase precipitation behaviour in novel aluminium crossover alloys was investigated. Thermal stability of ultrafine grains was achieved through controlled T-phase precipitation.

Keywords:

• Precipitation of T-phase (${\mathrm{M}\mathrm{g}}_{32}(\mathrm{Z}\mathrm{n}\mathrm{A}\mathrm{l}{)}_{49}$)
• ultrafine-grained aluminium crossover alloys
• in situ transmission electron microscopy
• DSC
• XRD

Acknowledgments

PDW and PJU are grateful for discussion with Roland Morak (AMAG Rolling GmbH).

CRediT authorship contribution statement

PDW: Conceptualization, Methodology, Investigation, Visualization, Writing - original draft. MAT, OR: Visualization, Writing - review & editing. CK, SG, TK: Investigation, Visualization, Writing - review & editing. PJU: Conceptualization, Supervision, Writing - review & editing. SP: Project administration, Conceptualization, Supervision, Writing - review & editing.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The research herein reported has been supported by both the European Research Council excellent science grant ‘TRANSDESIGN’ through the Horizon 2020 program [contract number 757961] and the Austrian Research Promotion Agency (Österreichische Forschungsförderungsgesellschaft) (FFG) in the project 3DnanoAnalytics [grant number FFG-No 858040].