High temperature indentation creep mechanisms of metal-ceramic nanolaminates

Abstract

Creep, as one of the mechanical properties for evaluating the resistance of deformation under a persistent stress, is extremely important in the application of metal/ceramic nanolaminates. In this work, the creep behaviors of Al/SiC nanolaminates with layer thickness of 10 nm and 100 nm were studied by means of nanoindentation in the temperature range from 25 °C to 150 °C. It was found that the stress exponent of nanolaminates for layer thickness of 100 nm increased with an increase in temperature. The stress exponent of Al was obtained by inverse methodology based on the finite element simulations, indicating that the creep mechanism changed from dislocation-grain boundary interaction to Coble creep. In the contrary, nanolaminates with layer thickness of 10 nm exhibited temperature-independent creep behaviors. This was rationalized by the co-deformation of Al and SiC layers beneath the indenter, which was dominated in the whole temperature range. In addition, all of these conclusions were further confirmed by the detailed transmission electron microscopic observation, the activation energy and the activation volume analysis.