Experimental investigation of distance effects between indenter and grain boundary on nanoindentation of Cu bicrystal

摘要

In order to study the effects of the distance between the indenter and the grain boundary (GB) onnnanohardness and plastic deformation under micro-anoscale, the nanoindentation tests onncopper bicrystals using a small size spherical indenter (40 nm radius) were analysed. Thendistance between the indenter and the GB was changed with different loads ranging from 20 ton1000 mN. The contact depth and nanohardness of the indents were calculated from load–ndisplacement curves. The results show that the nanohardness on the GB is much higher thannthose of other indents inside the grains, due to the strengthening effect of the GB on materialndeformation realised by hindering the movement of atoms and dislocation slip. The nanohardnessndescends sharply when the indenter is near the GB (1 mm); however, when the indenter is farnaway from the GB, the nanohardness increases slightly, and then decreases. It is also found thatnthere is load dependence on the GB; the law is different from those of the grain interior and othernsingle crystal materials.