Multi-scale iron-rich phases induce fine microstructures in Al-Zn-Mg-Cu-Fe alloys

Abstract

ABSTRACT Multi-scale Al7Cu2Fe and AlFeCu phases are formed in Al-Zn-Mg-Cu-Fe alloys after thermomechanical processing. These multi-scale particles significantly affect the size, morphology, and orientation of recrystallised grains and their corresponding mechanical properties. With increasing concentrations of iron-rich phase particles, the grain size in alloys is significantly reduced from 29.3 μm (0.0Fe wt.%) to 19.9 μm (0.2Fe wt.%) and 17.5 μm (0.4Fe wt.%). The volume fractions of copper, CubeND, and Q all decrease, and the R, Brass, and P textures form with high volume fractions in the #2 alloy. Both the yield and ultimate tensile strengths of the alloys decrease with an increasing iron-rich phase concentration. The highest r value (0.698) is obtained in the #2 alloy due to the improved microstructure and texture distributions from multi-scale iron-rich phases. Finally, the mechanisms of the iron-rich phase evolution, recrystallisation, and high formability in the alloys are introduced.