Abstract
Advanced nanodevices require reliable nanocomponents where mechanically-induced irreversible structural damage should be largely prevented. However, a practical methodology to improve the plastic reversibility of nanosized metals remains challenging. Here, we propose a grain boundary (GB) engineering protocol to realize controllable plastic reversibility in metallic nanocrystals. Both in situ nanomechanical testing and atomistic simulations demonstrate that custom-designed low-angle GBs with controlled misorientation can endow metallic bicrystals with endurable cyclic deformability via GB migration. Such fully reversible plasticity is predominantly governed by the conservative motion of Shockley partial dislocation pairs, which fundamentally suppress damage accumulation and preserve the structural stability. This reversible deformation is retained in a broad class of face-centred cubic metals with low stacking fault energies when tuning the GB structure, external geometry and loading conditions over a wide range. These findings shed light on practical advances in promoting cyclic deformability of metallic nanomaterials.
Highlights
Advanced nanodevices require reliable nanocomponents where mechanically-induced irreversible structural damage should be largely prevented
Through integrated state-of-the-art in situ nanomechanical testing and molecular dynamics (MD) simulation, we demonstrate that face-centred cubic (FCC) metallic nanocrystals with customdesigned low angle GBs (LAGBs) can accommodate exceptional reversible plasticity with negligible damage accumulation
We demonstrate a mechanism of grain boundary (GB)-mediated plastic reversibility that enables reversible deformation of nanosized materials beyond their simple elastic limit, and further validate it under the influences of multiple governing factors, as summarized in Supplementary Tables 1 and 2
Summary
Advanced nanodevices require reliable nanocomponents where mechanically-induced irreversible structural damage should be largely prevented. Both in situ nanomechanical testing and atomistic simulations demonstrate that custom-designed low-angle GBs with controlled misorientation can endow metallic bicrystals with endurable cyclic deformability via GB migration Such fully reversible plasticity is predominantly governed by the conservative motion of Shockley partial dislocation pairs, which fundamentally suppress damage accumulation and preserve the structural stability. The extraordinary plastic reversibility is governed by the collective motion of dissociated GB dislocations that readily overtake any nonconservative defect activities This energetically favoured conservative GB migration leads to the reversible deformation of metallic nanocrystals with a variety of intrinsic GB structures and external geometries under different loading conditions. These findings hold implications for interface engineering of metallic nanomaterials towards controllable reversible deformability, further boosting the optimal design of reliable nanocomponents from the bottom up
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