Effect of Yb additions on recrystallization behavior and properties of Al-Zn-Mg-Cu-Zr alloys

Al-Zn-Mg-Cu-Zr alloys containing Yb were prepared by cast metallurgy. Effects of 0.30 wt% Yb additions on the recrystallization behavior and the performances of Al-Zn-Mg-Cu-Zr alloys were investigated by hardness and electric resistance measurement, tensile test, stress corrosion cracking test measurement, optical microscopy and transmission electron microscopy. The results show that the ytterbium additions to Al-Zn-Mg-Cu-Zr aluminum alloys will increase the recrystallization temperature, obviously enhance the resistance to stress corrosion cracking and the fracture toughness property, and slightly increase the strengths and ductility at T6 treatment. It is attributed to the dispersoids with Yb containing. Those dispersoids homogeneously distributed in the Al matrix strongly pin dislocation and subgrain boundaries, which can significantly retard the recrystallization by inhibiting the nucleation of recrystallization.