Journal of Membrane Science, Vol.584, 290-299, 2019
Analysis of W/Mo alloying on hydrogen permeation performance of dual phase Nb-Ti-Ni alloys based on hydrogen chemical potentials
Substitution of Nb by the subgroup VI elements W and Mo was performed for dual phase Nb-Ti-Ni alloys containing a large fraction of primary bcc-(Nb) phase, particularly Nb45Ti27.5Ni27.5 and Nb56Ti23Ni21 . The alloying effect on the hydrogen permeation performance as a function of the W/Mo concentration was analyzed based on a description considering the chemical potential of hydrogen. The substitution of Nb by W or Mo leads to a reduced hydrogen solubility, which contributes to enhanced resistance to hydrogen embrittlement. Effect of WI Mo alloying on the mobility of H atom and thus the hydrogen permeability is dependent on the W/Mo concentration and the operative temperature. Simultaneous improved hydrogen mobility and mechanical stability of the membrane, especially at lower temperature T <= 523 K, was achieved after W/Mo alloying by 5 at%. Specifically, Nb40W5Ti27.5Ni27.5 and Nb46W5Mo5Ti23Ni21 membranes exhibit robust properties during hydrogen permeation cycle between 423 and 673 K.
Keywords:Nb-Ti-Ni dual phase alloy;W/Mo substitution;Hydrogen permeation;Hydrogen embrittlement;Hydrogen chemical potential