The grain size is a determinant microstructural feature to enable the activation of deformation twinning in hexagonal close-packed (hcp) metals. Although deformation twinning is one of the most effective mechanisms for improving the strength–ductility trade-off of structural alloys, its activation is reduced with decreasing grain size. This work reports the discovery of the activation of deformation twinning in a fine-grained hcp microstructure by introducing ductile body-centered cubic (bcc) nano-layer interfaces. The fast solidification and cooling conditions of laser-based additive manufacturing are exploited to obtain a fine microstructure that, coupled with an intensified intrinsic heat treatment, permits to generate the bcc nano-layers. In situ high-energy synchrotron X-ray diffraction allows tracking the activation and evolution of mechanical twinning in real-time. The findings obtained show the potential of ductile nano-layering for the novel design of hcp damage tolerant materials with improved life spans.

中文翻译：

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由增材制造产生的精细六边形微观结构中的界面介导孪晶诱导塑性

晶粒尺寸是一个决定性的微观结构特征，可以激活六方密堆积 (hcp) 金属中的变形孪晶。尽管变形孪生是改善结构合金强度-延展性权衡的最有效机制之一，但其活化会随着晶粒尺寸的减小而降低。这项工作报告了通过引入延展性体心立方 (bcc) 纳米层界面在细晶 hcp 微观结构中激活形变孪晶的发现。利用基于激光的增材制造的快速凝固和冷却条件来获得精细的微观结构，再加上强化的本征热处理，可以生成体心立方纳米层。原位高能同步加速器 X 射线衍射允许实时跟踪机械孪生的激活和演变。获得的研究结果表明，延展性纳米分层在设计具有改进寿命的 hcp 损伤耐受材料的新颖设计方面具有潜力。