Octahedral slip in nickel single crystals induced by scratch testing

The question of the crystallographic orientation effect on mechanical properties, behavior under load, or pattern of single crystals is relevant. One of the methods that makes it possible to achieve unambiguous mutual orientation of the material structure and the applied load is scratch testing. This research is aimed at establish the features of the formation of the deformation relief under various crystallographic conditions (orientation of the plane and direction of scratching). The paper presents the results obtained in experiments on scratch testing on single crystals of nickel. The face of a single crystal (010) and two directions of scratching [001], [1 ̅01] were investigated. The scratch testing parameters at which slip begins on the {111} planes have been determined. It is shown that the slip is activated most easily in the systems parallel to the direction of the indenter movement and in the systems oriented thereto at an angle of 45°. Three stages are identified on the scratch friction force vs normal load (F-N curve) and the correlation of the stages with the beginning of the shear traces formation is shown. The parameters of the transition to the third stage of the F-N curve and the magnitude of the friction force for scratch testing depend on the crystallographic orientation direction of the indenter movement.