Effects of Sc and Zr co-addition on structural evolution and mechanical properties of a 7xxx aluminum alloy with high Zn content
High Zn content 7xxx aluminum alloy with co-addition of Sc and Zr were prepared by traditional casting and thermomechanical processing technology in this paper.The effects of co-addition of Sc and Zr on the microstructure and mechanical properties of a 7xxx aluminum alloy with high Zn content was investigated by room temperature tensile test,scanning electron microscope,X-ray diffraction,and transmission electron microscope.The results show that the tensile strength of the newly designed and fabricated high Zn content aluminum alloy(w(Zn)=10.9%)is 769 MPa,while the elongation is 4.7%.The high Zn content directly leads to the formation of high density nanoscale η'phase,generating superior precipitation hardening effect.The primary Al3(Sc,Zr)phase formed by the co-addition of Sc and Zr helps to refine the solidification structures,while the secondary Al3(Sc,Zr)phase precipitated during aging effectively inhibits recrystallization and dislocation movements.These two aspects together result in exceptional grain boundary hardening effect.
high Zn content7xxx aluminum alloytraditional castingprecipitationmechanical property
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