Dynamic instantaneous dissolution of the precipitates in aged Mg-Zn-Zr alloy at high strain rate

• At a high strain rate of 3000 s⁻¹, β′1 precipitates in ZK60-T6 alloy undergo instantaneous partial dissolution and spheroidization within only 160 μs, evidenced by TEM observations. • Rod-shaped β′1 phases (average 48.5 nm length, 9.8 nm diameter) transform into spherical particles with an average diameter of 8.8 nm after dynamic loading, indicating significant morphological evolution. • The thermodynamic driving force for dissolution is enhanced by larger lattice distortion energy in the deformed β′1 phase compared to the Mg matrix, increasing the free energy difference between precipitate and matrix. • Accelerated Zn diffusion due to adiabatic temperature rise, high dislocation/vacancy density, and deviatoric stresses kinetically promote dissolution, contributing to hardness increase via solid solution strengthening, dislocation strengthening, and second-phase particle strengthening.