Rate dependency of depth in nanoindentation of polycrystalline NiTi

Department of Mechanical Engineering, the Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, China

^* Corresponding author. Tel.: +852 2358 8655; fax: +8522358 1543. E-mail address: meqpsun@ust.hk (Q.P. Sun).

Abstract

The recent increased use of shape memory alloys (SMAs) for engineering applications manifests the need of checking the aspect of rate in NiTi. The ability of models and experiments to accurately predict the rate dependency of function–rate relationship is important. This paper concentrates on the rate dependency of depth in nanoindentation of NiTi where different tips have been used. To explain the phenomena, hysteresis damping areas are investigated. The results show decreasing depth at higher rates is due to the amount of latent heat generated from phase transition and relaxation time for heat release.