Determination of hydrogen compatibility for Cu-Al-Ni-Fe-Mn cast alloys prepared by varying Al and Ni contents

Hydrogen compatibility of Cu-Al-Ni-Fe-Mn cast alloys was investigated via slow strain rate tensile tests in high-pressure hydrogen gas. Four types of alloys were prepared by varying the Al and/or Ni contents. Larger Al and Ni contents resulted in more elongated microstructures with smaller grains and more precipitates, respectively. The tensile strength of the alloys increased with larger Al and/or Ni contents, whereas the ductility decreased only by adding a larger amount of Al. The maximum tensile strength was produced by adding larger amounts of both Al and Ni, which was fairly higher than those of stable austenitic stainless steels. Despite the difference in the microstructures and tensile strengths of the alloys, the hydrogen contents and hydrogen diffusivities showed no substantial difference. Additionally, their reduction in area measured after the tensile tests was not degraded by the high-pressure hydrogen gas, revealing an excellent resistance to hydrogen embrittlement.