Lateral‐pushing induced surface lift‐up during nanoindentation of silicate glass.

Shear flow and/or densification have been long considered as the main mechanisms accounting for inelastic deformation during indentation of silicate glasses. However, the role of inelastic deformation during indentation of silicate glass is still debated. In this work, the cube‐corner indenter was chosen to perform the nano‐indentation tests on four different types of silicate glasses with a penetration depth of up to 0.5 μm. A 3D surface analysis method is developed to quantify the amplitude of the impression field. Based on this newly developed analysis approach, we have found that the shear flow and densification induced inelastic deformation of silicate glasses are visible as indentation, as pile‐up close to the indent, and as lift‐up far away from the indent. The lift‐up mechanism is revealed for the first time, which complements the previous well‐accepted pile‐up description. The lift‐up region is due to the increasing width of the indenter as it is pushed into the glass, which corresponds to the amount of glass volume pushed away laterally (lateral‐pushing) and can contribute up to ∼25% of the total volume above the original surface in soda‐lime silicate glass. We believe that this better quantification of inelastic deformation will contribute to reveal the structural evolution during nano‐indentation of silicate glass. [ABSTRACT FROM AUTHOR]