Extraordinary Strain Hardening from Dislocation Loops in Defect-Free Al Nanocubes

Abstract

The complex interaction of crystalline defects leads to strain hardening in bulk metals. Metals with high stacking fault energy (SFE), such as aluminum, tend to have low strain hardening rates due to an inability to form stacking faults and deformation twins. Here, we use in situ scanning electron microscopy (SEM) mechanical compressions to find that colloidally synthesized defect-free 114 nm Al nanocubes combine a high linear strain hardening rate of 4.1 GPa with a high strength of 1.1 GPa. These nanocubes have a 3 nm selfpassivating oxide layer that has a large influence on mechanical behavior and the accumulation of dislocation structures. Postcompression transmission electron microcopy (TEM) imaging reveals stable prismatic dislocation loops and the absence of stacking faults. MD simulations relate the formation of dislocation loops and strain hardening to the surface oxide. These results indicate that slight modifications to surface and interfacial properties can induce enormous changes to mechanical properties in high SFE metals.

Defect‐induced ferromagnetic ordering in pristine cuprous oxide nanocrystals at room temperature

“…The oxygen buffering capacity of ceria enables reversible switching between Ce 4+ /Ce 3+ oxidation states facilitated by oxygen vacancies to enhance the catalytic properties 9 . It has also been reported that dislocation loops in Al nanocubes leads to strain hardening, thereby improving the mechanical property of the material 10 . Moreover, the emergence of superconductivity in YBa 2 Cu 3 O 7‐δ is understood in terms of ordered oxygen vacancies in the basal plane 11 .…”

“…9 It has also been reported that dislocation loops in Al nanocubes leads to strain hardening, thereby improving the mechanical property of the material. 10 Moreover, the emergence of superconductivity in YBa 2 Cu 3 O 7-δ is understood in terms of ordered oxygen vacancies in the basal plane. 11 Similarly, the introduction of oxygen vacancies into the ZrO 2 lattice plays a crucial role in facilitating ionic conductivity, and there exists a critical concentration of oxygen vacancies where the oxide ion diffusion in the lattice is maximum, leading to higher oxide ion conductivity.…”