Deuterium permeation and retention behavior in copper-based brazing filler materials

•Assesses deuterium transport behavior in brazing filler materials used in fusion devices.•CuMnNi and CuGeNi demonstrate comparable deuterium permeability, yet they exhibit markedly different diffusion coefficients.•Deuterium retention in CuMnNi significantly exceeds that in CuGeNi.•CuGeNi exhibits a distinctly low deuterium adsorption capacity. Copper-based brazing filler materials are commonly employed in vacuum brazing techniques to achieve joining of plasma-facing components for ITER. In this work, gas-driven permeation (GDP) and thermal desorption spectroscopy (TDS) experiments have been performed to study the hydrogen isotopes permeation and retention behavior in two types of brazing filler materials (CuMnNi and CuGeNi metals). Experimental results show that CuMnNi filler exhibits the similar deuterium (D) permeability with CuMnNi filler but lower diffusion coefficients than CuGeNi filler. Three distinct peaks are observed between 380 K and 980 K for CuMnNi filler. However, no evident desorption peak is observed for CuGeNi filler. CuGeNi filler may be considered as a potential brazing filler material for reducing tritium inventory.