ON THE KINKING NONLINEAR ELASTIC RESPONSE OF MICA SINGLE CRYSTALS

Many materials near the earth's surface have been classified as nonlinear mesoscopic elastic (NME) solids because they exhibit nonlinear elastic behavior, hysteresis and discrete memory. Recently, it was shown that mica is a kinking non-linear elastic (KNE) solid because its mechanical response is dominated by the formation of incipient and regular kink bands [1]. It was also argued that the incipient kink bands – that are fully reversible – are the hysteretic mesoscopic units invoked to explain the response of NME solids. In this work - using repeated spherical nanoindentation experiments on three grades of mica single crystals - we present further evidence that the deformation of mica, including delaminations, that can be explained by invoking the presence of mobile dislocation walls, incipient and regular kink bands. Moreover, a model by which the number and distribution of dislocations under the indenter can be estimated is presented. The ramifications of this work to geology are discussed.

Ref. 1: M.W. Barsoum, A. Murugaiah, S.R. Kalidindi, T. Zhen, Kinking Nonlinear Elastic Solids, Nanoindentations and Geology, Phys. Rev. Lett. 92 (2004) 255508-1.