B. Fu; H. Abdolvand; R.J. Klassen
Journal of Materials Research and Technology 38 (2025) 5036–5051
This study investigates how crystal orientation and temperature affect the indentation creep behavior of pure
magnesium at 25 ◦C, 100 ◦C, and 180 ◦C using in-situ indentation and post-test EBSD analyses. The integrated
approach enables simultaneous evaluation of orientation-dependent activation parameters (ΔG0 and ΔV*),
athermal flow strength (̂τ), and the contribution of deformation twinning. Results show that creep is primarily
governed by obstacle-limited dislocation glide, with twinning contributing at lower temperatures at orientations
where slip is limited. At lower temperatures, indentation depth and lattice rotation around the indents are
strongly orientation-dependent, while at 180 ◦C these effects are less pronounced, suggesting more homogeneous
deformation. The activation energy (0.56–1.09 eV) and volume (10.28 b3–21.56 b3) increase with temperature
but are unaffected by orientation, indicating a consistent creep mechanism. The evolution of athermal flow
strength reflects a balance between strain hardening and dislocation recovery, with recovery dominating at
higher temperatures. Twinning, particularly {10 12}< 1011 > extension twins, was active at 25 ◦C and 100 ◦C
but suppressed at 180 ◦C, and was shown to evolve during the creep hold, confirming its role in accommodating
strain under constant load. These findings reveal that creep in Mg results from a temperature-dependent inter
play between dislocation glide, evolving internal obstacles, and twinning, offering new insight into the mech
anistic basis of time-dependent plasticity in hexagonal metals. The methodology presented in this paper provides
a robust framework for investigating time-dependent plasticity in Mg and can be extended to Mg alloys with
more complex microstructures.