Studies on the Effect of Crystallographic Orientation on Scratch Characteristics of Single Crystal Nickel

Owing to the unique tribological features, nickel alloys with rich nickel content are preferred over conventional alloys in tribological applications such as bearings and gears. Friction and wear problems are inevitable among mechanical components in various engineering applications. The design of these components are based on surface properties of materials. Therefore, it is required to understand the tribological behaviour of a structural material in order to determine a way for the optimum work efficiency of the material in the application. One way for an optimum friction and wear characteristics of materials is to analyse the anisotropic tribological response of the material and choose a better plane of contact for the application. To elucidate the best wear and friction properties, scratch experiments in combination with EBSD are performed on (100), (110) and (111) planes of bulk pure single crystalline nickel. Furthermore, the scratch test shows complex tribological responses and thus requires a deep insight on the influence of crystallographic orientation on elastic-plastic behaviour of the material during the scratch test. For this, similar scratch tests are performed using three dimensional molecular dynamics simulations, individually on the planes of single crystalline nickel with a rigid diamond indenter to understand the dislocation generation and propagation, material pile-up and surface topography of nickel during scratch. EAM potential is used for the interatomic potential among nickel atoms and Morse potential is used for interaction between nickel and carbon atoms in the diamond indenter. The indenter is made rigid and the interatomic potential among carbon atoms is ignored during the simulation. A correlation for the underlying mechanism and surface morphology during scratch is obtained for the results obtained from experiments and molecular dynamics simulations. Current work establishes an interplay between crystallography, friction and wear properties, deformation mechanisms, and surface morphology of the single crystalline nickel.