Nanoindentation of Ice Ih - Atomistic simulations

RUESTES, CARLOS J.; SANTOS-FLÓREZ, PEDRO ANTONIO; DE KONING, MAURICE

Conferencia; APS March meeting; 2020

American Physics Society

Using molecular dynamics simulations we study the mechanical response of ice Ih through nanoindentation tests perpendicular to the basal plane. Using a smooth spherical tip represented by a repulsive potential we explore the deformation mechanisms and hardness estimates for ice as described by the all-atom TIP4P/Ice potential and the coarse-grained mW models. We assess the sensitivity to the tip radius and the penetration rate both for low temperatures as well as for conditions close to the melting point, where the formation of a quasi-liquid layer (QLL) on the surface becomes relevant. We find that during plastic deformation the main mechanism for stress relief for the low temperatures is the amorphization of the crystalline ice bilayers. On the other hand, for high temperatures the plastic deformation occurs by bilayer-by-bilayer melting, consistent with previous literature. Considering the difference between the behaviors of the mW and TIP4P/Ice models, we observe that the latter also involves the nucleation and motion of dislocations. This is consistent with recent observations concerning uniaxial deformations and provides further indications that the absence of explicit protons in the mW model gives rise to excessive ductility.