I am usually quite thick, but notwithstanding my limitations, the boiling point of Helium is -268 deg C and the boiling point of Hydrogen is -252 deg C. To my mind they are both chuffing cold in their liquid state, and become gaseous at similar temperatures (within 16 degs C). So why does Hydrogen make metal (whatever element that metal may be) brittle, but not Helium?
I am afraid I lost the will to live after reading "cryogenics".