Strength dependent design method for the crystal orientation of diamond Berkovich indenter

Abstract Crystalline orientation on the pyramid faces of diamond Berkovich indenter is a crucial factor affecting the finished tip radius and edge radius, which are significant for the instrumented indentation test. In this work, the superposition principle is firstly introduced to model the dynamic micro tensile strength of diamond crystal in different directions and on any plane, and subsequently a dynamic micro tensile strength-dependent method is established to direct the design and fabrication of diamond Berkovich indenter. Mechanical polishing experiments are performed on three specially designed diamond Berkovich indenters, which have different crystalline orientations on the triangular based pyramid faces. The observations confirm that the material removal rate anisotropy appearing on any indenter face has a great dependence on the anisotropy of dynamic micro tensile strength of diamond crystal. This means that the dynamic micro tensile strength can be used to accurately find the ‘soft’ direction of the as-polished indenter face. Atomic force microscope (AFM) scanning results further validate that along the polishing direction the greater the dynamic micro tensile strength is on the indenter tip and edge, the smaller the indenter tip radius and edge radius will be finished.