Nano-indention was used to study the plastic flow behavior of body-centered cubic Ta(001) at 25 to 200C. Most notably, it was found that the shape of the load-displacement curves changes with increasing temperature. Only one large discontinuity marking the onset of plasticity was observed in room-temperature experiments, whereas multiple pop-ins separated by elastic reloading segments were observed at 200C. Detailed analysis of the load-displacement curves indicates that the lattice resistance decreases with increasing temperature, consistent with the mobilization of screw dislocations by thermal activation. Contributions from the oxide layer and/or thermal drift could be excluded.

Temperature Dependence of the Plastic Flow Behavior of Tantalum. M.M.Biener, J.Biener, A.M.Hodge: Philosophical Magazine Letters, 2010, 90[1], 35-42