Accounting for the Effects of Dislocation Climb Mediated Flow in Mg Alloy ZK10 Sheet

Tensile samples of an Mg alloy ZK10 sheet were tested at a range of temperatures and strain rates designed to rather evenly probe a range of Zener Hollomon parameter values, from ln(Z) ≈ 15 (10^–4 s⁻¹ and 623 K) up to ln(Z) ≈ 50 (10^–3 s⁻¹ and 300 K). In contrast with more commonly examined Mg alloy AZ31B sheet material, ZK10 sheet material shows modest strain anisotropy (r-value) at low temperatures for both 45° (r₄₅ ≈ 1.2) and TD (r_TD ≈ 1.4) sample orientations, despite showing evidence of significant prismatic slip of <a> dislocations, which often leads to high r-values at low temperatures. These low r-values become even lower (r₄₅ ≈ 0.84 and r_TD ≈ 0.89) at high temperatures. These behaviors are hypothesized to occur due to a distinct initial texture and deformation mechanism activity, which includes a modest level of tensile twinning and <c + a> slip at both room and elevated temperature. A version of the viscoplastic self-consistent (VPSC) code, which accounts for the kinematics of dislocation climb, is used to simulate the behavior of a textured Mg alloy ZK10 sheet reveals that both the glide of pyramidal <c + a> dislocations and the climb of basal < a > dislocations are required to describe the behavior at elevated temperatures.