Predictions of nanohardness and elastic modulus of thin film material with the quasicontinuum method

Quasicontinuum method was used to simulate the initial plastic deformation of both single crystals of aluminium and copper in nanoindentation test. The corresponding loading and unloading curves at different depths were obtained. Based on the calculated load-depth curves, the contact stiffnesses, nanohardnesses and elastic moduli for thin film materials were evaluated using the Oliver-Pharr method and were compared with experimental results in the publised literatures. The results show that the contact stiffness-displacement curves are linear, and the size effect exists in nanohardness measurement, but doesn't in elastic modulus measurement. The calculated nanohardnesses and elastic moduli of both single crystals of aluminium and copper are (0.584 +/not superset of 0.013) and (84.088 +/not superset of 0.332) GPa, (0.755 +/not superset of 0.027) and (131.833 +/not superset of 4.449) GPa, respectively, which agree with the experiments indicating that the presented approach is reliable for prediction of the nanohardness and elastic modulus of thin film materials.