Direct observation of autonomous self-healing in silver

JL Wang and QH Xu and MH Sun and JY Xu and P Chen and BH Yu and ZQ Wu and ZT Chen and XD Huang and HC Sun and L Liao and C Cai and XM Li and LF Wang and XZ Tian and Z Xu and S Meng and WL Wang and XD Bai, MATTER, 7 (2024).

DOI: 10.1016/j.matt.2024.07.009

Although the concept of self-healing has undergone a recent resurgence of interest in polymers and other soft materials, it is extremely rare for metal solids to autonomously self-repair structural damage without any external trigger. Here, we report on the direct in situ observation of such an autonomous solid-state self- healing behavior in nanoscale silver (Ag) by utilizing atomic-resolution transmission electron microscopy (TEM). Two representative kinds of structural damage-both nanopores and nanocracks-are observed to undergo automatic self-repair at room temperature and well below (down to 173 K) without any external intervention. Importantly, such an autonomous self-healing phenomenon does not occur in gold (Au) at room temperature, as it is hindered by the stronger Au-Au bonding resulting from the known relativistic effect. A combination of atomistic imaging and molecular dynamics simulation unravels that the self-healing process is accomplished through surface- mediated diffusion of Ag atoms as driven by chemical potential imbalance due to the Gibbs-Thomson effect.

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