The unique and desirable behavior of nanocrystalline materials (NCMs) is singularly attributed to the large number of grain boundaries relative to their coarse grain material (CGM) counterparts, which translates into a significant fraction of atoms (up to 50%) located in interfacial regions. Thus, the atomic structure and properties of the grain boundaries are of extreme importance in dictating the macroscopic physical and mechanical properties of NCMs. However, one of the biggest challenges is to produce durable nanostructures that will not lose their properties during service. Hardness, strength, fracture toughness, creep and fatigue experiments have been conducted to assess the properties of nanostructured Cu and their durability under temperature and stress. Molecular dynamics studies have been used to investigate how segregated dopant atoms affect the energetics of grain boundaries and their implications on grain growth in nanocrystalline metals by our group.