Abstract
Experiments and simulations show that the microstructural stability of nanocrystalline Cu can be improved by adding impurity atoms, such as Sb, which migrate to the grain boundaries. Cu100-xSbx alloys are cast in three compositions (Cu-0.0, 0.2 and 0.5 at.%Sb) and subsequently processed into nanocrystalline form by equal channel angular extrusion (ECAE). The presence of Sb atoms at the grain boundaries increases the recrystallization temperature to 400 °C compared to 200 °C for pure nanocrystalline Cu, which was verified by measurements of microhardness, ultimate tensile strength, grain size using TEM, and Auger electron spectroscopy. Molecular dynamics (MD) simulations were performed using a wider range of Sb compositions (0.0 to 1.0 at.%Sb) to study the underlying mechanisms associated with stability. MD simulations show that Sb atoms reduce excess grain boundary energy and that 0.2 and 0.5 at.%Sb is enough to stabilize the nanocrystalline Cu microstructure.
