Exceptional stress corrosion cracking resistance-strength synergy of Al-Zn-Mg-Cu alloys via tailored nano-sized particles

High-strength Al-Zn-Mg-Cu alloys are extensively utilized in the aeronautics sector for lightweighting, but they are notoriously susceptible to stress corrosion cracking (SCC). Herein, a novel strategy was proposed to mitigate SCC in Al-Zn-Mg-Cu alloys by manipulating nano-sized particles. Mn-bearing dispersoids significantly curbed hydrogen (H) production and infiltration into Al matrix, and T precipitates notably reduced H concentration and occupancy at grain boundaries, intermetallic compound particles and interfaces of η precipitates, which were potentially implicated in hydrogen embrittlement (HE). The synergistic effects of Mn-bearing dispersoids and T precipitates yielded an optimal balance of strength and SCC resistance in Al-Zn-Mg-Cu alloys. The Al-Zn-Mg-Cu alloys, exhibiting an optimal combination of strength (752 MPa), ductility (11.3%), and excellent stress corrosion resistance, were successfully fabricated through the manipulation of nano-sized particles.