The features of the plastic deformation of a micrograined magnesium alloy AZ31 under tension in the temperature range 4.2–295 K were studied. The samples were deformed in two structural states: the initial (after eight passes of equal channel angular pressing, 8ECAP) and annealed (after isothermal annealing at 573 K) states. In both cases, with decreasing temperature, an increase in the yield strength, strain hardening coefficient, and a decrease in ductility were observed. The dependence of the hardening coefficient of the deformation is nonmonotonic compared to the initial one, which is explained by an increase in twinning activity due to an increase in grain size upon annealing. The low Hall–Petch parameters for the yield strength at room temperature indicate a high activity of the basal slip of the dislocations, due to the mixed texture that forms after 8ECAP and does not change radically upon annealing. The yield strength of the studied polycrystals is determined by the thermofluctuation motion of mainly basal dislocations. The empirical parameters of this motion in the temperature range 4.2–295 K, obtained from the analysis of the temperature dependences of the yield strength and activation volume, correspond to the mechanism of interaction of dislocations with local obstacles formed by impurity atoms and forest dislocations.

中文翻译：

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AZ31微晶镁合金低温塑性变形

研究了微晶镁合金 AZ31 在 4.2-295 K 温度范围内受拉时的塑性变形特征。样品在两种结构状态下变形：初始（经过八次等通道角挤压，8ECAP）和退火（在 573 K 等温退火后）状态。在这两种情况下，随着温度的降低，观察到屈服强度、应变硬化系数和延展性降低。变形硬化系数的相关性与初始值相比是非单调的，这是由于退火时晶粒尺寸增加导致孪晶活动增加的原因。室温下屈服强度的低霍尔-佩奇参数表明位错的基底滑移活动高，由于在 8ECAP 后形成的混合织构并且在退火时不会发生根本变化。所研究多晶的屈服强度主要由基底位错的热波动运动决定。从屈服强度和活化体积的温度依赖性分析中获得的这种运动在 4.2-295 K 温度范围内的经验参数对应于位错与由杂质原子和森林位错形成的局部障碍相互作用的机制。