Differential Scanning Calorimetry Determination of the Hydrogen Solubility in E110opt and E635 Zirconium Alloys

The hydride dissolution and formation temperatures in domestic zirconium alloys E110opt and E635 are determined by differential scanning calorimetry for samples with a hydrogen content of 50–700 ppm. Solvus curves and van’t Hoff dependences are constructed for a zirconium alloy–hydrogen system, and the specific enthalpies of hydride dissolution and formation in the E635 and E110opt alloys are calculated. The enthalpies of hydride formation and dissolution in the E110opt alloy is found to be higher than in the E635 alloy and foreign zirconium alloys, and the E635 alloy is comparable with a foreign Zircaloy-4 alloy in this parameter. The temperature hysteresis in the E635 alloy is found to be smaller than in other alloys.