The Positron Spectroscopy of the Zr-1Nb Alloy after Modification by High-Current Pulsed Electron Beam

This paper presents the results of an experimental study of the structure of the Zr-1Nb alloy after modification by a high-current pulsed electron beam. The defective and phase structures were studied by the X-ray diffraction, positron lifetime spectroscopy, and Doppler broadening methods. The surface layer modification under electron-beam treatment was caused by the formation of a liquid phase and its subsequent congelation at the end of the pulse. It is shown that after the modification considerable changes of the annihilation parameters related to the change of the defect structure on the surface and in the volume of the material took place. Depending on the irradiation regime, the redistribution of positron annihilation probability between the two types of defects was observed. The pulsed electron beam irradiation of the Zr-1Nb alloy significantly changed the surface and structure of defects to a depth of up to 100 mu m. It is shown that after the alloy modification by a pulsed electron beam, dislocation loops and vacancy-type defects prevailed.