The major concern in the deep geological disposal of spent nuclear fuels include sulfide-induced corrosion and stress corrosion cracking of copper canisters. Sulfur diffusion into copper canisters may induce copper embrittlement by causing Cu₂S particle formation along grain boundaries; these sulfide particles can act as crack initiation sites and eventually cause embrittlement. Copper alloys are designed in this study to prevent the formation of Cu₂S along grain boundaries as a proactive approach to cope with the sulfur-induced copper embrittlement.

Alloying elements that can act as chemical anchors to suppress sulfur diffusion and the formation of Cu₂S along grain boundaries are investigated based on the understanding of the microscopic mechanism of sulfur diffusion and Cu₂S precipitation along grain boundaries. Copper alloys are experimentally manufactured by using vacuum arc melting and cold rolling to validate the alloying elements.

Microstructural analysis using scanning electron microscopy with energy dispersive spectroscopy demonstrates that Cu₂S particles are not formed at grain boundaries but randomly distributed within grains in all the vacuum arc-melted Cu alloys (Cu-Si, Cu-Ag, and Cu-Zr). The mechanical properties of the vacuum arc-melted and cold-rolled Cu alloys are evaluated, and discussed based on the observed microstructures.