A POSITRON-ANNIHILATION STUDY OF THE EVOLUTION OF AMORPHIZATION IN NB3SN BY MECHANICAL MILLING

In an attempt to probe the effect of vacancy-related defects on the cr ystalline-to-amorphous phase transformation; positron annihilation lif etime measurements were performed on Nb3Sn with the A15 structure as a function of mechanical milling. The lifetime spectra were deconvolute d into two components. Both components increased during the initial st age of milling, consistent with an increase in the concentration of th e vacancy-type defects and void-type defects formed as a result of mil ling, The formation of these types of defects plays an important role in the amorphization reaction of A15 Nb3Sn. (C) 1998 Elsevier Science B.V. All rights reserved.