Precipitation behaviour in AlMgZnCuAg crossover alloy with coarse and ultrafine grains
Patrick Willenshofer, Matheus A. Tunes, Christina Kainz, Oliver Renk, Thomas Kremmer, Stefan Gneiger, Peter J. Uggowitzer, Stefan Pogatscher
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 — Mg32(Zn,Al)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.