A high-strength AlZnMg alloy hardened by the T-phase precipitates

An Al-7.60Zn-2.55Mg (wt.%) alloy with a characteristically high Mg-to-Zn atomic ratio has been investigated for its strength and hardening precipitates in comparison with that of 7150 alloy. It is shown that this alloy yields a rather high strength upon thermal ageing. Interesting is that this high-strength alloy is hardened by the coherent polyhedral T-phase [(AlZn)49Mg32] particles and their early-stage precipitates, which is very different from that of other high-strength AA7xxx AlZnMg(Cu) alloys hardened by the disc-like precipitates of the η-type phases.