Temperature dependence of the plastic flow behavior of tantalum.

Nanoindention has been used to study the plastic flow behavior of bcc Ta(001) in the temperature range 25-200°C. Most notably, it is found that the shape of the load-displacement curves changes with increasing temperature. Only one large discontinuity marking the onset of plasticity is observed in room-temperature experiments, whereas multiple pop-ins separated by elastic reloading segments were observed at 200°C. 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 can be excluded. [ABSTRACT FROM AUTHOR]