Measuring anisotropy in Young’s modulus of copper using microcantilever testing

Focused ion beam machining was used to manufacture microcantilevers 30 µm by 3 µm by 4 µm with a triangular cross section in single crystal copper at a range of orientations between. These were imaged and tested using AFM/nanoindentation. Each cantilever was indented multiple times at a decreasing distance away from the fixed end. Variation of the beam’s behavior with loading position allowed a critical aspect ratio (loaded length:beam width) of 6 to be identified above which simple beam approximations could be used to calculate Young’s modulus. Microcantilevers were also milled within a single grain in a polycrystalline copper sample and electron backscattered diffraction was used to identify the direction of the long axis of the cantilever. The experimentally measured values of Young’s modulus and their variation with orientation were found to be in good agreement with the values calculated from the literature data for bulk copper.