Microstructure and superior quenching sensitivity of a novel Sc, Zr alloyed Al-Zn-Mg-Cu alloy

This paper studies a novel Al-Zn-Mg-Cu-Mn-Sc-Zr alloy that exhibits outstanding quenching sensitivity with a quench-hardening depth of more than 150 mm. Jominy end quenching allows the alloy to obtain different quenching rates. The Brinell hardness of the aged alloy with a quenching rate of 27 degrees C/s is 154 HB; when the quenching rate drops to 1.5 degrees C/s, its hardness value loses about 8%, which is 142 HB. The quenching-induced equilibrium precipitates heterogeneously precipitated at the grain boundary and the incoherent phase interfaces (E phase, Al-6(Mn, Fe) phase), but no heterogeneous precipitates are observed along the coherent L1(2)-Al-3(Sc, Zr) particles. After artificial aging, densely distributed nano-scaled atomic clusters and G.P zones, as well as grain boundary precipitation free zones (PFZs) were observed.

Automated summary

This paper investigates a novel Al-Zn-Mg-Cu-Mn-Sc-Zr alloy with excellent quenching sensitivity and a quench-hardening depth of more than 150 mm. Different quenching rates affect the hardness of the alloy, and after artificial aging, various precipitates are observed on the grain boundaries and different phase interfaces.