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Self‐Healing and Shape Memory Effects in Gold Microparticles through the Defects‐Mediated Diffusion
Advanced Science ( IF 14.3 ) Pub Date : 2017-07-07 , DOI: 10.1002/advs.201700159 Oleg Kovalenko 1 , Christian Brandl 2 , Leonid Klinger 1 , Eugen Rabkin 1
Advanced Science ( IF 14.3 ) Pub Date : 2017-07-07 , DOI: 10.1002/advs.201700159 Oleg Kovalenko 1 , Christian Brandl 2 , Leonid Klinger 1 , Eugen Rabkin 1
Affiliation
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Some metal alloys subjected to irreversible plastic deformation can repair the inflicted damage and/or recover their original shape upon heating. The conventional shape memory effect in metallic alloys relies on collective, or “military” phase transformations. This work demonstrates a new and fundamentally different type of self‐healing and shape memory in single crystalline faceted nano and microparticles of pure gold, which are plastically deformed with an atomic force microscope tip. It is shown that annealing of the deformed particles at elevated temperatures leads to nearly full recovery of their initial asymmetric polyhedral shape, which does not correspond to global energy minimum shape. The atomistic molecular dynamic simulations demonstrate that the shape recovery of the particles is controlled by the self‐diffusion of gold atoms along the terrace ledges formed during the particles indentation. This ledge‐guided diffusion leads to shape recovery by the irreversible diffusion process. A semiquantitative model of healing developed in this work demonstrates a good agreement with the experimental data.
中文翻译：
通过缺陷介导的扩散对金微粒的自我修复和形状记忆效应
一些遭受不可逆塑性变形的金属合金可以修复所造成的损坏和/或在加热时恢复其原始形状。金属合金中的常规形状记忆效应依赖于集体或“军事”相变。这项工作证明了纯金的单晶多面纳米和微粒中一种新的，根本不同类型的自我修复和形状记忆，这些微粒通过原子力显微镜尖端塑性变形。结果表明，在高温下对变形的颗粒进行退火会导致其初始的不对称多面体形状几乎完全恢复，这不符合整体能量最小形状。原子分子动力学模拟表明，颗粒的形状恢复受金原子沿着颗粒压痕过程中形成的阶地壁架的自扩散控制。壁架引导的扩散通过不可逆的扩散过程导致形状恢复。在这项工作中开发的康复半定量模型表明与实验数据有很好的一致性。
更新日期：2017-07-07
中文翻译：
通过缺陷介导的扩散对金微粒的自我修复和形状记忆效应
一些遭受不可逆塑性变形的金属合金可以修复所造成的损坏和/或在加热时恢复其原始形状。金属合金中的常规形状记忆效应依赖于集体或“军事”相变。这项工作证明了纯金的单晶多面纳米和微粒中一种新的，根本不同类型的自我修复和形状记忆，这些微粒通过原子力显微镜尖端塑性变形。结果表明，在高温下对变形的颗粒进行退火会导致其初始的不对称多面体形状几乎完全恢复，这不符合整体能量最小形状。原子分子动力学模拟表明，颗粒的形状恢复受金原子沿着颗粒压痕过程中形成的阶地壁架的自扩散控制。壁架引导的扩散通过不可逆的扩散过程导致形状恢复。在这项工作中开发的康复半定量模型表明与实验数据有很好的一致性。
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