High-throughput investigation of temperature-dependent creep mechanisms in Mg-Zn alloys using nanoindentation

Abstract A novel high-throughput methodology is proposed to investigate the influence of Zn alloying and temperature on the creep mechanisms of Mg through a combination of a Mg/Mg-Zn diffusion couple and advanced nanomechanical testing. Systematic nanoindentation creep tests were conducted at room temperature (RT) and elevated temperatures (100 °C, 200 °C and 300 °C) within individual grains in a Mg/Mg-Zn diffusion couple with Zn content ranging from 0 to 0.8 at%. Electron backscattered diffraction-assisted trace analysis was employed to characterize the activated deformation mechanisms, including twinning and dislocation slip. The activation volume and creep activation energy were analyzed to elucidate the fundamental creep mechanisms as functions of temperature and Zn content. At the low temperature regime (RT-100 °C), the creep activation energy was ≈80 kJ mol −1 , indicating that twinning dominated deformation mechanisms. At the high temperature regime (>200 °C), all alloys converge to a relatively high activation energy, of the order of 150 kJ mol −1 . This is in good agreement with the activation energy reported for cross-slip deformation mechanisms. The results indicate that the derived activation energy aligns with the transition in creep deformation mechanisms, shifting from twin boundary migration to cross-slip. Moreover, Zn alloying significantly enhances creep resistance, particularly within the temperature range of RT to 200 °C.