Hydrogen solubility limits in α- and β-zirconium

Abstract

Specimens of pure zirconium and Zr–20Nb alloy were charged to different hydrogen concentrations from the gas phase at 673 K. Before and after charging with hydrogen, the Zr–20Nb specimens were annealed in vacuum at 1123 K for 1 h and cooled to room temperature within about 30 min to produce a β-Zr structure. Some of these specimens were annealed further at 773 K for about 500 h to completely transform them to ( α-Zr+ β-Nb) phase. The specimens were analyzed for hydride transition temperatures using differential scanning calorimetry and for hydrogen concentration using hot vacuum extraction mass spectrometry. The hydrogen solubility limits found for pure Zr are in good agreement with the previously reported values. The solubility limits found in β-Zr are about two orders of magnitude higher than the solubility limits in α-Zr and the solubility limits found in the aged Zr–20Nb alloy are very close to those in α-Zr.