Effect of niobium on the microstructure, hydrogen embrittlement, and hydrogen permeability of NbxHf(1−x)/2Ni(1−x)/2 ternary alloys

The influence of niobium (Nb) on the microstructure, hydrogen embrittlement, and hydrogen permeability of the NbxHf(1−x)/2Ni(1−x)/2 ternary alloys has been studied in particular. The results show that the quantity of the primary (Nb, Hf) phase decreases with the increase of Nb content from 14 mol% to 16 mol%, and then increases with the increase of the Nb content from 16 mol% to 40 mol%. The Nb14Hf43Ni43 alloy is brittle at all temperatures from 523 K to 673 K, as it possesses the largest amount of the Bf-HfNi compound; however, the Nb40Hf30Ni30 alloy has high resistance to hydrogen embrittlement at all temperatures from 523 K to 673 K, as it possesses the largest amount of the primary (Nb, Hf) phase. The hydrogen permeability (Φ) increases with the increase in Nb content, as the quantity of the primary (Nb, Hf) phase in the NbxHf(1−x)/2Ni(1−x)/2 ternary alloys also increases with the increase in Nb content.