Abstract The pre-existing twin boundaries play an important role in the mechanical behaviors of metals. In the present work, we studied the bending deformation of [100]-oriented α-Fe nanowires seeded with 〈111〉/{112} twin boundaries using atomistic simulations. Bending behaviors along two different orientations were investigated. The initially flat twin boundaries become curved with a high density of 1/6 〈111〉/{112} partial dislocations under bending when the neutral plane intersects with twin plane along [0 1 - 1] direction, whereas could transform to the nonconventional {110} interfaces under bending when the neutral plane intersects with twin plane along [111] direction. The bent α-Fe nanowires could recover to the original state upon unloading, leading to a unique pseudoelasticity. The driving force for shape recovery primarily arises from the high interfacial energy, i.e. curved {112} twin boundaries or the transformed {110} interfaces. We further characterized the recoverability by the ratio η of the nanowire size (external length scale) to twin boundary spacing (internal length scale). This η-dependent recoverability matches well with the experimental data at large length scale. The present work may help understand the unique mechanical properties associated with twin boundaries in metals.

中文翻译：

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弯曲下孪晶α-Fe纳米线的伪弹性

摘要 预先存在的孪晶界在金属的力学行为中起着重要作用。在目前的工作中，我们使用原子模拟研究了以<111>/{112}孪晶边界为种子的[100]取向的α-Fe纳米线的弯曲变形。研究了沿两个不同方向的弯曲行为。当中性面沿 [0 1 - 1] 方向与孪晶面相交时，最初平坦的孪晶边界变得弯曲，具有 1/6 <111>/{112} 部分位错的高密度弯曲，而可以转变为非常规 {当中性面与双晶面沿[111]方向相交时，110}界面发生弯曲。弯曲的 α-Fe 纳米线在卸载后可以恢复到原始状态，从而产生独特的伪弹性。形状恢复的驱动力主要来自高界面能，即弯曲的{112}孪晶边界或转变的{110}界面。我们通过纳米线尺寸（外部长度尺度）与孪晶边界间距（内部长度尺度）的比率 η 进一步表征了可恢复性。这种依赖于 η 的可恢复性与大长度尺度的实验数据很好地匹配。目前的工作可能有助于理解与金属中孪晶界相关的独特机械性能。这种依赖于 η 的可恢复性与大长度尺度的实验数据很好地匹配。目前的工作可能有助于理解与金属中孪晶界相关的独特机械性能。这种依赖于 η 的可恢复性与大长度尺度的实验数据很好地匹配。目前的工作可能有助于理解与金属中孪晶界相关的独特机械性能。