Temperature-dependent transition from amorphization to interfacial melting in ice nanomechanics

A comprehensive understanding of ice's nanoscale mechanical behavior is critical for predicting its performance in natural and engineered systems. While prior studies have extensively characterized bulk ice and pristine ice surface, the mechanical response of ice at the nanoscale, particularly under the influence of foreign surface, remains poorly understood.

Here, we integrate nanoindentation experiments with molecular dynamics (MD) simulations to unravel temperature-dependent deformation mechanisms in hexagonal ice (Ih) with the presence of foreign surface-ice interface.

Experiments reveal an anomalous forward-displacing feature after loading, indicative of unusual relaxation dynamics. This observation is consistent with MD results showing a rapid decline in mechanical strength and elastic modulus with increasing temperature, alongside a distinct crossover regime in Young's modulus. Atomic-scale analysis demonstrates that these relaxation dynamics triggers a crossover in deformation mechanism: stress-induced amorphization dominates plasticity at low temperatures, whereas interfacial ice melting governs deformation at higher temperatures. The latter process involves a quasi-liquid layer (QLL) at the ice-indenter interface, which promotes molecular extrusion and stress relaxation. These findings establish a mechanistic link between nanoscale deformation dynamics and microscale mechanical responses, offering key insights for applications ranging from ice-phobic surfaces to extraterrestrial ice exploration.