Al-Zn-Mg-Cu （7050） alloy has been selected as a model system for the investigation of precipitate stability，subject to proton irradiation during solar flare events.10 MeV Cl³⁺ heavy-ions were used as surrogate，for accelerated simulation experiment at room temperature，up to a fluence of 5.0×10¹⁸ ions/m².The dimensional and structural stability of strengthening precipitates η′-MgZn₂ and η-MgZn₂ were analyzed，and their impacts upon nanohardness were evaluated.Characterizations based on transmission electron microscopy confirmed that：（1） nano-scale dispersed η′-MgZn₂ demonstrated high dimensional stability，however partly prone to ballistic mixing and vacancy-induced dissolution，thereby reducing the total precipitate population；（2） equilibrium phase η-MgZn₂ were distributed at grain boundaries and within grain interiors，exhibited pronounced coarsening due to radiation-enhanced diffusion，but the precipitate population remained almost constant.Nanohardness evaluation indicated negligible irradiation hardening，probably associated with the contribution of irradiation-induced defect clusters，which hindered dislocation motion，and compensated the softening caused by the partial loss of η′-MgZn₂.The current study shows that it is crucial to focus on the dissolution of η′-MgZn₂ and the coarsening of η-MgZn₂，and mitigate the effects by enhanced precipitate/matrix interface stability and increased defect sink densities，so as to enhance the radiation tolerance of materials.