The effect of additional elements on hydrogen permeation properties of melt-spun Ni-Nb-Zr amorphous alloys

Abstract

The (Ni 0.6Nb 0.4) 45Zr 50X 5(X = Al, Co, Cu, P, Pd, Si, Sn, Ta or Ti) alloy ribbons were produced by the melt-spinning technique. All ribbon specimens were confirmed to have a single amorphous phase by XRD analysis. The crystallization temperature of the melt-spun (Ni 0.6Nb 0.4) 45Zr 50X 5 (X = Al, P, Pd, Si or Sn) amorphous alloys are higher than that of the (Ni 0.6Nb 0.4) 50Zr 50 amorphous alloy (727 K). Although the hydrogen permeability of the (Ni 0.6Nb 0.4) 45Zr 50X 5 (X = Si, Sn, Ta or Ti) amorphous alloys could not be measured due to severe embrittlement during the permeation test, the (Ni 0.6Nb 0.4) 45Zr 50X 5 (X = Al, Co, Cu, P or Pd) amorphous alloys had high ductility which was enough to measure the permeability. The hydrogen permeabilities of the (Ni 0.6Nb 0.4) 45Zr 50Co 5 and the (Ni 0.6Nb 0.4) 45Zr 50Cu 5 amorphous alloys were 2.46 × 10 -8 and 2.34 × 10 -8[mol · m -1 · s -1 · Pa -1/2] at 673 K, respectively. The (Ni 0.6Nb 0.4) 45Zr 50P 5 amorphous alloy possesses the lowest permeability of 1.36 × 10 -8[mol · m -1 · s -1 · Pa -1/2] at 673 K among the alloys where the permeability was measured. The reduction of the permeability in the (Ni 0.6Nb 0.4) 45 Zr 50P 5 amorphous alloy is thought to be due to the preferential formation of Zr-P atomic pairs which may suppress the hydrogen solubility and hydrogen diffusivity in the alloy. Since the heat of mixing for Zr-P atomic pairs is negatively larger than that for other pairs such as Ni-P and Nb-P. It is concluded that the Ni-Nb-Zr-X (X = Co or Cu) amorphous alloys have high potential to hydrogen permeable membranes.