Superplastic behaviour of Al-Mg-Zn-Zr-Sc-based alloys at high strain rates.

Superplastic deformation behaviour of two aluminium-based AA7XXX type alloys with Sc and Zr additives distinguished by the presence and absence of coarse eutectic Al 9 FeNi particles are compared. An alloy with Al 9 FeNi particles exhibits high strain rate superplasticity at constant strain rate range of 5×10 −3 –8×10 −2 s −1 with elongation of 915% due to extensive dynamic recrystallisation. Effective activation energy of superplastic deformation, surface relief of deformed samples, and grain structure evolution are analysed. Particle-depleted zones are found in the alloy with Al 9 FeNi particles at strains higher than 1.25. [ABSTRACT FROM AUTHOR]