Long-distance interface diffusion induced non-volume-conserved deformation in self-supported submicron-sized aluminum pillars

The plastic deformation of a solid generally conserves the local mass/volume of the sample. Here, we show that under elevated temperature and low strain rate, this may not hold for the widely used compression test geometry with self-supported aluminum pillars in the submicron range. Plastic flow can instead proceed with continuous shortening, while the overall diameter and shape remain constant. This apparent non-conservation results from a rarely-reported interface-diffusion-mediated deformation, when interface diffusion between the metal and the native oxide layer is rejuvenated to mediate mass relocation spreading over an interfacial area far exceeding the dimensions of the self-supported pillar, thus providing large continuous plastic strain.

Automated summary

Under elevated temperature and low strain rate, the compression test with self-supported aluminum pillars may not conserve the local mass/volume of the sample. Plastic flow can occur with continuous shortening while maintaining a constant overall shape. This non-conservation is due to interface diffusion between the metal and the native oxide layer, allowing mass relocation and providing large continuous plastic strain.