Micropillar compression of Al/SiC nanolaminates

Al/SiC nanolaminates possess an excellent combination of mechanical strength and flexibility. While nanoindentation provides a reasonable estimate of the mechanical properties such as Young's modulus and hardness of these materials, the stress state under nanoindentation is extremely complex. Micropillar compression has become an attractive method of studying the mechanical properties of materials at small length scales in a nominally homogeneous stress state. In this work, micropillars of Al/SiC nanolaminate were fabricated using focused ion beam milling. Compression testing was carried out using a flat-end nanoindenter head. The actual displacement of the pillar during micropillar compression was deconvoluted by subtracting the "extraneous" displacements of the system. Fractographic analysis showed that Al squeezes out between the SiC layers and that a mutual constraint is observed between the hard and soft layers. Numerical finite element modeling was also employed to provide physical insight into the deformation features of the multilayered pillar structure and agreed well with the experimental observations.