X-ray stress analysis of oxidized Zr-based alloys

摘要

The results of X-ray diffraction analysis of macroscopic stresses in oxide layers and substrate of zirconium alloys are presented in this contribution. Stresses were studied on the tubular specimens of three types of alloys: Zr1Nb, low tin Zircaloy-4 and Zr-Nb-Sn alloy (ZIRLO) which were simultaneously exposed for various time in four environments: 360 °C water, 360°C water with 70 ppm Li as LiOH, steam at 400 °C and steam at 450 °C. The courses of compressive stresses σ vs. oxide thickness are quantitatively different for two type of alloys in all of environments used. The courses for ZIRLO seem to be less dependent on corrosion conditions. In the range of the large oxide thicknesses (> 10 μm) two cases were observed: a) the value of stress falls down to zero, b) the values stay on some levels which differ for different alloys and environments. Only tensile residual stresses were indicated within substrate of all samples investigated. Microstructure characteristics (crystallite size and lattice strains) were evaluated for oxide layers and the metal underlying.