The nanometric scale ploughing friction and wear behaviour of a pyramidal diamond indenter sliding against a face-centred cubic silver (100) surface is investigated by means of parallel molecular dynamic (MD) simulations of nanoindentation followed by nanoscratching. The relationship between the friction coefficient, the hardness and the indenter orientation is studied. The simulations were performed using three different indenter orientations. For each orientation, simulations were performed at an indentation depth of 5 and 10 A, and a scratching length of 210 A. in order to study the behaviour of the friction coefficient and the hardness as a function of depth we performed the simulations for one of the orientations at depths of 5, 10 and 30 A. The simulations show that the friction coefficient is dependent on both the orientation of the indenter and the indentation depth. The results also show that the friction coefficient increases as the depth increases, whereas the contact pressure decreases and the scratch hardness decreases slightly. With a shallow indent of 5 A, no sub-surface defects were observed beneath the scratch groove, but with the deeper indents of 10 and 30 A dislocations in the {111} planes are observed beneath the scratch groove. These dislocations propagate in the (110) direction; each dislocation consists of the intersection of stacking faults on two {111} planes and each stacking fault is bounded by two Shockley partial dislocations.
展开▼
