Distorted icosahedral Ni5Nb3Zr5 clusters in the as-quenched and hydrogenated amorphous (Ni0.6Nb0.4)0.65Zr0.35 alloys

► Little change in the local structure of a-(Ni0.6Nb0.4)65Zr35 was shown after 7.8at% H2 charge. ► Ab initio calculation indicates Ni-centered Ni5Nb3Zr5 icosahedron is the most stable cluster. ► XAFS results of Ni K-edge can be well represented by distorted Ni-centered Ni5Nb3Zr5 cluster. ► A large tetrahedron in this cluster can trap hydrogen without changing in the local structure.