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The Strongest Size in Gradient Nanograined Metals.
Nano Letters ( IF 10.8 ) Pub Date : 2020-01-23 , DOI: 10.1021/acs.nanolett.9b05202 Penghui Cao 1, 2
Nano Letters ( IF 10.8 ) Pub Date : 2020-01-23 , DOI: 10.1021/acs.nanolett.9b05202 Penghui Cao 1, 2
Affiliation
Conventional polycrystalline metals become stronger with decreasing grain size, yet softening starts to take over at the nanometer regime, giving rise to the strongest size at which the predominate strengthening mechanism switches to softening. We show that this critical size for the onset of softening can be tuned by tailoring grain size gradient, and raising in the gradient shifts the size toward the smaller value. The decrease in the strongest size is prompted by mitigation of grain boundary-mediated softening processes accompanying by enhanced intragranular plastic deformations. We found that the nanograins smaller than 6 nm, mainly involving intergranular sliding in homogeneous structures, reveal anomalous plastic deformation in gradient systems, which is mediated by partial dislocation nucleation, faulting and twinning activated in a gradient stress field. The results on extended dislocation slip and gradient plasticity, stemming from the structure heterogeneity, shed light on an emerging class of heterogeneous nanostructured materials of improved strength-ductility synergy.
中文翻译:
梯度纳米晶粒金属中最大的尺寸。
常规的多晶金属随着晶粒尺寸的减小而变得更强,但软化作用开始在纳米范围内发生,从而产生了最强的尺寸,在该尺寸下,主要的强化机制转换为软化作用。我们表明,可以通过定制晶粒度梯度来调整开始软化的临界尺寸,并且梯度的增大会使尺寸向较小的值移动。最强尺寸的减小是由晶界介导的软化过程的减轻引起的,该过程伴随着增强的颗粒内塑性变形。我们发现小于6 nm的纳米颗粒主要涉及均质结构中的晶间滑动,在梯度系统中显示出异常的塑性变形,这是由部分位错成核介导的,断层和孪晶在梯度应力场中被激活。由结构异质性引起的位错滑移和梯度可塑性扩展的结果为新兴一类提高强度-延展性协同作用的异质纳米结构材料提供了启示。
更新日期:2020-01-24
中文翻译:
梯度纳米晶粒金属中最大的尺寸。
常规的多晶金属随着晶粒尺寸的减小而变得更强,但软化作用开始在纳米范围内发生,从而产生了最强的尺寸,在该尺寸下,主要的强化机制转换为软化作用。我们表明,可以通过定制晶粒度梯度来调整开始软化的临界尺寸,并且梯度的增大会使尺寸向较小的值移动。最强尺寸的减小是由晶界介导的软化过程的减轻引起的,该过程伴随着增强的颗粒内塑性变形。我们发现小于6 nm的纳米颗粒主要涉及均质结构中的晶间滑动,在梯度系统中显示出异常的塑性变形,这是由部分位错成核介导的,断层和孪晶在梯度应力场中被激活。由结构异质性引起的位错滑移和梯度可塑性扩展的结果为新兴一类提高强度-延展性协同作用的异质纳米结构材料提供了启示。