The Dislocation Reaction of Pure Aluminum during Cryogenic Uniaxial Tension and Its Impact on Mechanical Properties

• Cryogenic deformation mechanisms of pure aluminum were investigated via TEM characterization and LAMMPS molecular dynamics simulations. • Lomer and Lomer–Cottrell dislocation locks formed during cryogenic deformation hinder dislocation glide, enhancing strength. • TEM analysis revealed a significant reduction in stacking fault energy (SFE) at 83 K, verified by LAMMPS simulations. • The lower SFE at cryogenic temperatures promotes dislocation dissociation and improves both strength and plasticity. Aluminum alloys exhibit a phenomenon of "simultaneous enhancement of strength and plasticity" (referred to as " dual-enhancement") under cryogenic deformation conditions. However, the intrinsic mechanisms underlying this strengthening behavior, particularly the deformation dynamics at the microscale and their correlation with macroscopic properties, remain insufficiently studied. This paper focuses on pure aluminum as the research subject, experimentally observing and analyzing the "dual strengthening and toughening" phenomenon during cryogenic deformation. Transmission electron microscopy (TEM) was employed to characterize the samples, revealing the deformation mechanisms from the perspectives of dislocation reactions and stacking fault energy (SFE). Furthermore, molecular dynamics (MD) simulations of the deformation process were conducted using LAMMPS software. By integrating simulation results with experimental data, the intrinsic mechanisms of the "dual strengthening and toughening" phenomenon in pure aluminum under cryogenic deformation were thoroughly analyzed. The findings provide a theoretical foundation for further understanding the deformation behavior of aluminum alloys in low-temperature environments.