High temperature micropillar compression of Al/SiC nanolaminates

The effect of the temperature on the compressive stress-strain behavior of Al/SiC nanoscale multilayers was studied by means of micropillar compression tests at 23 C and 100 C. The multilayers (composed of alternating layers of 60 nm in thickness of nanocrystalline Al and amorphous SiC) showed a very large hardening rate at 23 C, which led to a flow stress of 3.1 ± 0.2 GPa at 8% strain. However, the flow stress (and the hardening rate) was reduced by 50% at 100 C. Plastic deformation of the Al layers was the dominant deformation mechanism at both temperatures, but the Al layers were extruded out of the micropillar at 100 C, while Al plastic flow was constrained by the SiC elastic layers at 23 C. Finite element simulations of the micropillar compression test indicated the role played by different factors (flow stress of Al, interface strength and friction coefficient) on the mechanical behavior and were able to rationalize the differences in the stress-strain curves between 23 C and 100 C.