Determination of Solid Solubility Limit of Hydrogen in Alpha Zirconium by Internal Friction Measurements

The general background internal friction variation with temperature is considered to be due to the oscillations of the dislocation segments in metal crystals. When these segments are strongly pinned by impurities or precipitates, then the back-ground level reduces considerably. Under certain experimental conditions, zirconium hydride precipitates along the dislocations so as to pin the dislocation segments firmly. For a given composition of Zr-H alloy, the maximum temperature at which there is a measurable decrease in internal friction, due to precipitation, indicates the maximum solubility at that temperature. Thus, the solid solubility of hydrogen in iodide zirconium can be determined by a close study of the precipitation of hydride using the internal friction technique. Such a technique has been used to determine the solubility limit of hydrogen in iodide zirconium, Zr-0.25Gd and reactor grade sponge zirconium in the temperature range of 100 to 300°C. However, in the latter case the technique was found to be inadequate.