Mechanical behavior of FCC single crystals at finite temperatures in the presence of point defects

Molecular dynamics simulations have been performed to study the effect of temperature and the presence of various types of point defects on the mechanical response of copper. Nanoindentation and uniaxial tests have been modeled to compare different loading conditions. Anisotropy effects have been also added to the study by applying the uniaxial load in various crystallographic orientations. The yield stress in all cases decreases with increased temperature for both perfect crystals and crystals with point defects. However, the temperature sensitivity of the yield stress is significantly lowered by the presence of defects in simulated nanoindentation and compression tests, while the combined effect of point defects and elevated temperature on the yield in tension is less than in the other loading conditions. The deformation mechanism which causes this effect is described, and points towards possible explanations for previously observed variations in nanomechancial testing between common experimental methods.