Comment on “elastic-plastic deformation in ion-exchanged aluminosilicate glass by loading rate dependent nanoindentation”

As part of a recent study Li et al. (2018) [1] proposed as a proof of inhomogeneous shear flow at indentation site in oxide glasses the existence of both a nano pattern on the residual imprint as revealed by atomic force microscopy and numerous discrete events on the load displacement curve, called bursts. Both were reported to be loading rate dependent. Here, using the same experimental set up, we provide experimental evidence that discrete bursts existence and loading rate sensitivity can be attributed to the displacement sensor noise floor and to data sampling rate issues respectively. We also show the nano pattern present on the faces of the indentation imprint to be extremely repeatable, to not depend neither on glass composition nor on loading rate as it is the result of the stamping onto the glass surface of the indenter surface roughness generated by its machining process.