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1. (2021) Accounting for the Effects of Dislocation Climb Mediated Flow in Mg Alloy ZK10 Sheet. In: Miller V.M., Maier P., Jordon J.B., Neelameggham N.R. (eds) . The Minerals, Metals & Materials Series. Springer, Cham. https://doi.org/10.1007/978-3-030-65528-0_6

   https://doi.org/10.1007/978-3-030-65528-0_6  

   Ritzo, Michael A.; Agnew, Sean R. (February 2021, Magnesium Technology 2021)

   Miller, Victoria M.; Maier, Petra; Jordon, J. Brian; Neelameggham, Neel R. (Ed.)

   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 (rTD ≈ 1.4) sample orientations, despite showing evidence of significant prismatic slip of dislocations, which often leads to high r-values at low temperatures. These low r-values become even lower (r45 ≈ 0.84 and rTD ≈ 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  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  dislocations and the climb of basal < a > dislocations are required to describe the behavior at elevated temperatures. 

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2. Revealing deformation mechanisms in Mg–Y alloy by in situ deformation of nano-pillars with mediated lateral stiffness

   https://doi.org/10.1557/jmr.2019.124  

   Zhang, Dalong; Jiang, Lin; Wang, Xin; Beyerlein, Irene J.; Minor, Andrew M.; Schoenung, Julie M.; Mahajan, Subhash; Lavernia, Enrique J. (May 2019, Journal of Materials Research)

   In our previous study, we observed a lack of $$\left\{ {10\bar{1}2} \right\}$$ twinning in a deformed Mg–Y alloy, which contributed to the observed yield “symmetry.” However, the effects of texture and grain size on polycrystalline deformation made it difficult to fully understand why twinning was not active. Therefore, we report herein in-depth study by in situ transmission electron microscopy, i.e., in situ TEM. The in situ deformation of nano-sized Mg–Y pillars revealed that prismatic slip was favored over twinning, namely, the critical stress required to activate prismatic slip was lower than that for twinning. This finding diametrically differs from that reported in other nano/micro-pillar deformation studies, where twinning is always the dominant deformation mechanism. By measuring the critical stresses for basal, prismatic, and pyramidal slip systems, this in situ TEM study also sheds light on the effects of the alloying element Y on reducing the intrinsic plastic anisotropy in the Mg matrix. 

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3. Why rolled Mg-Al-Ca-Mn alloys are less responsive to aging as compared to the extruded

   https://doi.org/10.1016/j.scriptamat.2023.115513  

   Bhattacharyya, J.J.; Sasaki, T.T.; Nakata, T.; Agnew, S.R. (August 2023, Scripta Materialia)

   Dilute Mg-Al-Ca-Mn alloys exhibit excellent strength-ductility combinations in the peak-aged condition due to ordered, single atomic layer Guinier-Preston (GP) zones. The present work explains why rolled sheet material is softer and less responsive to aging, as compared to extruded. Using crystal-plasticity modeling, it is shown that the initial texture of the rolled material permits the soft modes, basal slip and twinning, to accommodate more of the strain during in-plane tension, and they are less responsive to hardening by the finely dispersed GP zones. Even with the same number density of GP zones, the extruded material is stronger in tension along the extrusion axis due to an initial texture which forces higher relative activity of prismatic slip, a mode previously shown to be strongly affected by the GP zones. The present work reemphasizes the significant role of the initial texture in determining the strength and anisotropy of non-cubic metals and alloys. 

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4. Hardness anisotropy in Mg: The influence of extension twining and 〈c + a〉 dislocation activity under nanoindentations

   https://doi.org/10.1016/j.scriptamat.2025.116832  

   Motallebi, Reza; Lai, Yi-Cheng; Walker, Christopher C; Dong, Jiaqi; Pharr, George M; Xie, Kelvin Y (October 2025, Scripta Materialia)

   Nanoindentation was performed on individual grains of a polycrystalline Mg sample with c-axis declination angles ranging from parallel (0°) to perpendicular (90°) to the c-axis. Hardness was highest at ∼0°, decreased up to ∼55°, and then increased at ∼90° to an intermediate level. At ∼0°, high-density 〈c + a〉 dislocations extended deep into the crystal, contributing to high hardness. At ∼55°, 〈c + a〉 dislocations were confined near the indent, and occasional extension twinning reoriented the crystal to ∼45°, promoting 〈a〉 slip in both matrix and twin, leading to low hardness. At ∼90°, extension twinning reoriented the crystal to ∼0°, inducing texture hardening and intermediate hardness. Despite the complex stress state in nanoindentation, which fundamentally differs from the uniaxial stress in bulk tensile and compression tests, the combined contributions of dislocation and twinning still give rise to measurable hardness anisotropy, suggesting nanoindentation as a high-throughput technique for probing orientation-dependent mechanical behavior in Mg. 

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5. Large plasticity in magnesium mediated by pyramidal dislocations

   https://doi.org/10.1126/science.aaw2843  

   Liu, Bo-Yu; Liu, Fei; Yang, Nan; Zhai, Xiao-Bo; Zhang, Lei; Yang, Yang; Li, Bin; Li, Ju; Ma, Evan; Nie, Jian-Feng; et al (July 2019, Science)

   Lightweight magnesium alloys are attractive as structural materials for improving energy efficiency in applications such as weight reduction of transportation vehicles. One major obstacle for widespread applications is the limited ductility of magnesium, which has been attributed to 〈 c + a 〉 dislocations failing to accommodate plastic strain. We demonstrate, using in situ transmission electron microscope mechanical testing, that 〈 c + a 〉 dislocations of various characters can accommodate considerable plasticity through gliding on pyramidal planes. We found that submicrometer-size magnesium samples exhibit high plasticity that is far greater than for their bulk counterparts. Small crystal size usually brings high stress, which in turn activates more 〈 c + a 〉 dislocations in magnesium to accommodate plasticity, leading to both high strength and good plasticity. 

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