Influence of trace Ti on the microstructure, age hardening behavior and mechanical properties of an Al-Zn-Mg-Cu-Zr alloy

The influence of trace Ti on the microstructure and precipitation process of a Zr-containing Al-Zn-Mg-Cu alloy was investigated. The introduction of Ti results in not only the refinement of α-Al grains, but also an early-stage age hardening behavior during aging treatment process. High-resolution transmission electron microscopy results indicate that Ti can decrease the coarsening tendency of L12 precipitates and accelerate the growth rate of GP II as well as its evolution to η' phase. The mechanism was discussed. Accordingly, the tensile strength, elongation and wear property were obviously improved.