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

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, Cube_ND, 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.

KEYWORDS:

• Al-Zn-Mg-Cu alloy
• iron-rich phases
• microstructure
• texture
• mechanical properties

Acknowledgments

This work was supported by the National Key Research and Development Program of China (No. 2016YFB0300801), National Natural Science Foundation of China (Nos.51871029, 51571023 and 51301016), Government Guided Program-Intergovernmental Bilateral Innovation Cooperation Project (No. BZ2019019).

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China (Nos. 51871029, 51571023 and 51301016), National Key Research and Development Program of China (No. 2016YFB0300801), Government Guided Program-Intergovernmental Bilateral Innovation Cooperation Project (No. BZ2019019), the Opening Project of State Key Lab of Advanced Metals and Materials (No.2020-ZD02).