Multi-scale simulation of the deformation in nano-indentation under different crystal orientations

The nano-indentation process of an fcc Al film under three different crystal orientations (x[1 1 1], y[(1) over bar 1 0], z[(1) over bar (1) over bar 2]; X[(1) over bar (1) over bar 2], y[1 1 1], z[(1) over bar 1 0] and x[1 (1) over bar 0], Y[0 0 1], z[(1) over bar (1) over bar 0]) are studied using the quasi-continuum method. The load-displacement responses of the film under different crystal orientations are presented respectively. The local atomics in the regions where sharp deformation occurred are plotted to analyse their mechanisms on atomic scale. The results show that the micromechanisms of the deformation in the film are different for different crystal orientations. Under the orientation of x[1 1 1], y[(1) over bar 1 0], Z[(1) over bar (1) over bar 2], in which the indentation direction is parallel to the close-arranged plane, the deformation in the film is mainly dominated by the dislocation nucleation caused by the slip of the plane, and the hardness and the out-of-plane displacement of the crystal are large. Under the x[(1) over bar (1) over bar 2], y[1 1 1], z[(1) over bar 1 0] orientation, in which the indentation direction is perpendicular to the close-arranged plane, the deformation in the film is mainly dominated by the deformation twinning, and both the hardness and the out-of-plane displacement of the crystal are the largest. Under the x[1 (1) over bar 0], y[0 0 1], z[(1) over bar (1) over bar 0] orientation, in which the indentation direction is at some degrees inclined to the close-arranged plane, the deformation in the film starts from a small dislocation line nucleating on a slip plane at the beginning of the loading and then deformation twinning is formed with the increasing loading, and the hardness and the out-of-plane displacement of the crystal are the smallest.