In situ Mechanical Testing of Contacts Between Nanoscale Bodies: Measuring the Load-dependence of Contact Area.

Mechanical tests were performed on a silicon/diamond nanocontact. Using in situ transmission electron microscopy (TEM) and matched atomistic simulations, the contact area was measured during loading and unloading. The results agreed within uncertainty, and both experiment and simulation data showed significant hysteresis. While the unloading curves could be fit to a continuum model, yielding a realistic value for elastic modulus, this model overpredicted the contact area upon loading by an average of 40%. The implications of these results for real-world nanoscale contacts are that the contact area upon loading can deviate significantly from continuum predictions, even when the behavior upon unloading is well described by these models