Transition to chip serration in simulated cutting of metallic glasses

Cutting of metallic glasses produces as a rule serrated and segmented chips in experiments, while atomistic simulations produce straight unserrated chips. We demonstrate here that with increasing depth of cut – with all other parameters unchanged – chip serration starts to affect the morphology of the chip also in molecular dynamics simulations. The underlying reason is the shear localization in shear bands. As the distance between shear bands increases with increasing depth of cut, the surface morphology of the chip becomes increasingly segmented. The parallel shear bands that formed during cutting do no longer interact with each other when their separation is $$\gtrsim $$ ≳ 10 nm. Our results are analogous to the so-called fold instability that has been found when machining nanocrystalline metals. Graphic abstract