The hydrogen permeable alloy 1, wherein {HEAD ~ the fourth element} comprises {TAIL ~ Cu}, and 
comprises
The hydrogen permeable alloy 1 , wherein { HEAD ~ the fourth element } comprises { TAIL ~ Cu } , and
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH