Hydrogen Permeability Of Alloys Research Articles

Modelling of fast hydrogen permeability of alloys for membrane gas separation

The method of measuring the specific hydrogen permeability is used to study various alloys that are promising for gas separation installations. The nonlinear boundary value problem of hydrogen permeability complying with the specific features of the experiment and its modifications taking into account the high transfer rate is presented. Substantial difference from the quasi-equilibrium model (Richardson approximation in the assumption of the equilibrium Sieverts’ law near the surface) has been discussed. The model is tested on published experimental data on Ta77Nb23 alloy.

Relationship between hydrogen permeation and microstructure in Nb–TiNi two-phase alloys

The relationship between the microstructure and hydrogen permeability of the as-cast two-phase Nb–TiNi alloys is investigated and discussed on the basis of the mixing rule. The alloy compositions consisted of the bcc-(Nb, Ti) and B2–TiNi phases are expressed as (Nb4Ti46Ni50)1−x(Nb85Ti13Ni2)x. The alloy for x = 0.19 has a fully eutectic structure of the (Nb, Ti) and TiNi phases in the as-cast state. The hydrogen permeability of this alloy corresponds to that of a model alloy in which these two phases are distributed randomly. The primary TiNi and (Nb, Ti) phases are formed in the alloys for x < 0.19 and x > 0.19, respectively. Their volume fractions decrease and increase with x, respectively. According to the mixing rule, the hydrogen permeability of alloys having a primary (Nb, Ti) phase can be expressed as the model alloy in which the primary phase is isolated in the eutectic structure. However, the hydrogen permeability of alloys having a primary TiNi phase is higher than that expected for the above model alloy.

Hydrogen permeation of the Zr 65Al 7.5Ni 10Cu 12.5Pd 5 alloy in three different microstructures

We have investigated the hydrogen permeation of the melt-spun Zr 65Al 7.5Ni 10Cu 12.5Pd 5 alloy in the supercooled liquid, the quasi-crystalline particle-dispersed glassy and the crystalline states. The hydrogen permeability of this alloy is highest in the supercooled liquid state and is lowest in the crystalline state, compared among the three different structures. The hydrogen permeability of the melt-spun alloys consisting of quasi-crystalline particles-dispersed in the glassy state is intermediate between the single phase glassy, and the crystalline alloys. This is presumably because the Zr content in the residual glassy phase decreases after the primary precipitation of the icosahedral-phase (i-phase), resulting in a decrease in the hydrogen permeability.