Inhibitory effect of low-angle grain boundaries on the creep behavior of gradient nano-grained Cu: A molecular dynamics study

Gradient nano-grained (GNG) structures are renowned for their superior strength-toughness synergy. Within GNGs, low-angle grain boundaries (LAGBs), a type of low-energy grain boundary, have been identified and contribute to the mechanical and thermal stability of materials. This study uses molecular dynamics simulations to examine the impact of varying LAGB ratios on the creep behavior of GNG Cu at temperatures ranging from 720 K to 1080 K and stresses from 0.3 GPa to 0.7 GPa. The results show that LAGBs significantly enhance creep resistance, particularly at higher concentrations, temperatures, and stresses. LAGBs inhibit grain growth and influence mechanisms like diffusion and sliding. They suppress intragranular sliding and rotation, thus inhibiting creep. Furthermore, LAGBs prevent phase transformation from HCP to FCC and increase twin concentration, promoting deformation twinning. These findings, supported by changes in grain boundary morphology, atomic structure analysis, and statistical data, underline the critical role of LAGBs in enhancing the creep resistance of GNG metals.