Influence of additives induced microstructural parameters on mechanical behavior of (111)-oriented nanotwinned microcrystalline copper

Abstract

Depth sensing nanoindentation experiments were performed to investigate the strain rate dependent-independent behaviors of nanotwinned microcrystalline Cu. The specimens were electro-deposited using three different additives, which resulted in controlled variations in microstructural parameters, viz., grain size, and twin spacing. One of the three samples with the lowest twin lamella spacing showed a lower stress exponent, which might result in enhanced ductility. The stress exponent and activation volume increased with increasing twin spacing. In contrast, the hardness revealed a dependence on the effective length scale considering the weighted average of the twin spacing and grain size. The mechanical properties obtained by introducing nanotwins in coarser initial grain size are comparable to nanotwinned nanocrystalline materials. Thus, the possibility of using a coarser initial grain size for nanotwinned materials paves the way for a new paradigm with a broader range of nanotwinned materials.