  Under hydrostatic pressure, alpha-quartz undergoes solid-state mechanical
amorphization wherein the interpenetration of SiO4 tetrahedra occurs and the
material loses crystallinity. This phase transformation requires a high
hydrostatic pressure of 14 GPa because the repulsive forces resulting from the
ionic nature of the Si-O bonds prevent the severe distortion of the atomic
configuration. Herein, we experimentally and computationally demonstrate that
e-beam irradiation changes the nature of the interatomic bonds in alpha-quartz
and enhances the solid-state mechanical amorphization at nanoscale.
Specifically, during in situ uniaxial compression, a larger permanent
deformation occurs in alpha-quartz micropillars compressed during e-beam
irradiation than in those without e-beam irradiation. Microstructural analysis
reveals that the large permanent deformation under e-beam irradiation
originates from the enhanced mechanical amorphization of alpha-quartz and the
subsequent viscoplastic deformation of the amorphized region. Further,
atomic-scale simulations suggest that the delocalized excess electrons
introduced by e-beam irradiation move to highly distorted atomic configurations
and alleviate the repulsive force, thus reducing the barrier to the solid-state
mechanical amorphization. These findings deepen our understanding of
electron-matter interactions and can be extended to new glass forming and
processing technologies at nano- and microscale.
