Insight on the mechanism by which microstructural characteristic influenced creep resistance of dilute Mg–Mn–Zn alloys in varied processing conditions

Abstract

The significance of creep performance in Mg alloys is underscored by their widespread use as thermally conductive structural components in industries. This work investigated the influence of microstructure characteristics on the creep properties of dilute Mg–Mn–Zn alloys under varied processing conditions. The specimen designations were: AH (as-homogenized), AE (as-extruded), and AC (as-hot compressed). The creep resistance was as follows: AH > AE > AC, although AC exhibited the best mechanical properties. AH primarily exhibited cross-slip and twinning. AE displayed cross-slip and twinning for coarse non-dynamically recrystallized (non-DRXed) grains, and basal slip and pyramidal slip for fine DRXed grains. AC had basal slip and pyramidal slip. The highest creep resistance for AH resulted from the stable solid solution strengthening and the interplay between twinning and cross-slip. In contrast, AC, with the lowest creep resistance, experienced an accelerated creep strain due to precipitate coarsening and frequent grain boundary sliding. A combination of pipe diffusion-controlled and grain boundary diffusion-controlled slip contributed 57% to the steady creep rate. This work provides a considerable insight for the application of Mg alloys as thermally conductive structural components.

Keywords

• Mg alloys
• Microstructure
• Mechanical property
• Creep resistance