Determining the activation energy and volume for the onset of plasticity during nanoindentation

TitleDetermining the activation energy and volume for the onset of plasticity during nanoindentation
Publication TypeJournal Article
Year of Publication2006
AuthorsMason, JK, Lund, AC, Schuh, CA
JournalPhysical Review B
Volume73
Issue5
Date Published2006/02//
Abstract

Nanoindentation experiments are performed on single crystals of platinum, and the elastic-plastic transition is studied statistically as a function of temperature and indentation rate. The experimental results are consistent with a thermally activated mechanism of incipient plasticity, where higher time-at-temperature under load promotes yield. Using a statistical thermal activation model with a stress-biasing term, the data are analyzed to extract the activation energy, activation volume, and attempt frequency for the rate-limiting event that controls yield. In addition to a full numerical model without significant limiting assumptions, a simple graphical approximation is also developed for quick and reasonable estimation of the activation parameters. Based on these analyses, the onset of plasticity is believed to be associated with a heterogeneous process of dislocation nucleation, with an atomic-scale, low-energy event as the rate limiter.