Comparative analysis of precipitation hardening mechanisms in Al-7075 alloy under different quenching media

This study explores the influence of cooling rate on precipitation behavior and mechanical properties in Al 7075 alloy through a combined experimental and simulation-based approach. Samples subjected to air cooling (AC), water quenching (WQ), and laser surface remelting (LSR) were examined using scanning transmission electron microscopy (STEM) to capture the evolution of precipitates during natural and artificial aging. Complementary kinetic Monte Carlo (kMC) simulations revealed atomic-scale clustering kinetics under varied cooling conditions, establishing a direct correlation with experimentally observed precipitate size and density. Results indicate that WQ promotes fine GP zones and η′ precipitates, leading to high hardness through coherency strengthening, while AC yields coarser η precipitates favoring Orowan looping. Despite ultrafast cooling, LSR delays hardening due to diffusion-limited cluster formation. This integrative framework offers mechanistic insights into age-hardening pathways and emphasizes the role of quench rate in tailoring strength of naturally aged aluminum alloys.