Local crack suppression and activation of plastic flow via electron irradiation in oxide glasses

• Electron irradiation activates local plastic flow in glasses inducing a softening noticeable as reduction in hardness. • Irradiation induced changes in deformation resistance ΔH/H 0 exhibit a distinct increase from 10 A/m 2 on forward. • Brittle-Ductile-Transition manifests in a suppression of indentation cracking from 10 A/m 2 on forward. • Nanoindentation can resolve electron irradiation induced changes in the mechanical properties of pristine glass surfaces. The present study demonstrates the potential of electron irradiation for local modification of the mechanical behavior of oxide glasses via In-SEM nanoindentation. The experiments were performed with cube-corner indenter tip under various electron beam conditions on Fused Silica, soda-lime-silica glass and the borosilicate glass Boroplate. The results show that electron irradiation is a powerful tool to locally activate plastic flow processes in order to target crack suppression upon nanoindentation. The glasses deformation resistance (i.e. hardness) can be adjusted with switching the intensity of the electron beam or the strain rate for indentation while changes in elastic modulus remain moderate. The change of the deformation resistance, determined by parameter ΔH/H 0 , shows a distinct increase at beam intensities from which on forward crack suppression has been detected, serving as indication for brittle-to-ductile transition.