Microstructure, Ductility and Hydrogen Permeability of Nb-Ti-Zr-Ni Alloys

Abstract

A series of Nb 40 Ti x Zr 12 Ni 48Àx alloys with different Ti/Ni ratios were prepared by arc melting in a purified argon atmosphere. The Ti/Ni ratio affected microstructures, crystal structures, ductility and hydrogen permeability (È) of these alloys. The values of hydrogen permeability È for the Nb 40 Ti x Zr 12 Ni 48Àx alloys increased with increasing temperature and were higher than those of pure Pd above 573 K. Hydrogen permeability at 673 K, i.e., È 673K and the volume fraction of the primary phase in the Nb 40 Ti x Zr 12 Ni 48Àx alloys increased with increasing Ti/Ni ratio. The present work demonstrated that hydrogen permeation properties of the Nb 40 Ti 20 Zr 12 Ni 28 alloy are superior to those of the Nb 40 Ti 18 Zr 12 Ni 30 one which was reported to be the best one in the Nb 40 Ti 30Àx Zr x Ni 30 alloys.

Effect of elements addition on hydrogen permeability and ductility of Nb40Ti18Zr12Ni30 alloy

“…Therefore, it is desirable to develop a new low-cost membrane by minimum addition or absence of Pd with high hydrogen permeability (Φ), ductility and resistance to the hydrogen embrittlement. In recent years, researchers have investigated the V-based [3][4][5], Nb-Ti-Ni (or Co) [6,7] and some amorphous alloy membranes [8][9][10] and resistance to the hydrogen embrittlement [11]. However, hydrogen permeation could not be measured due to the hydrogen embrittlement if the thickness of this alloy membrane is lower than 0.3 mm.…”

“…There are two possible methods to solve the hydrogen embrittlement of this alloy. One is to reduce the content of Zr so as to reduce Φ and to enhance ductility [11]. The other is to add a small amount of other elements.…”

Design of (Nb, Mo)40Ti30Ni30 alloy membranes for combined enhancement of hydrogen permeability and embrittlement resistance

“…It exhibits strong HE resistance in a much larger hydrogen pressure range than that for Nb-based solid solution alloys. However, the hydrogen permeability of Nb 40 Ti 30 Ni 30 is not quite satisfactory for the practical applications 48 . In this work, the substitution of Nb by Mo in Nb 40 Ti 30 Ni 30 was investigated with respect to microstructural features and hydrogen dissolution, diffusion and permeation.…”

Changes in microstructure, ductility and hydrogen permeability of Nb–(Ti, Hf)Ni alloy membranes by the substitution of Ti by Hf

“…It is found that appropriate substitution of Ti by Zr can induce a much higher hydrogen permeability (because of the higher hydrogen affinity of Zr than that of Ti) and comparable other properties [32,33]. Nevertheless, excessive addition of Zr leads to low ductility and serious hydrogen embrittlement due to the microstructural change and the inappropriately high hydrogen solubility [34]. Therefore, much of current research focuses on compositional modifications in these alloys to tailor the microstructures and hydrogen solubility and diffusivity for improved performance.…”

“…mechanically sealed with copper gaskets, these alloys must have at least some ductility. Most simply, a material that can be broken easily by hammering is qualitatively defined as brittle [32][33][34], while non-broken materials are defined as ductile.…”