Composition-dependent cluster-to-precipitate transformation in novel high-strength and heat-resistant Al–Zn–Mg–Cu alloys

The insufficient thermal stability remains a bottleneck for the broader application of high-strength Al–Zn–Mg(–Cu) alloys. Here, we develop a novel low-Zn/Mg alloy where clusters exhibit preferential growth and smooth compositional continuity with T-type precipitates, enabling efficient cluster-to-precipitate transformation and resulting in high-density thermally stable T-type precipitates. Therefore, the developed alloy achieves a yield strength of ∼515 MPa and retains ∼430 MPa (>80%) after long-term thermal exposure at 150°C for 1000 h, significantly outperforming conventional age-hardenable Al alloys. This work proposes a composition-matching strategy between clusters and precipitates for developing high-strength and heat-resistant Al alloys.