A quasi-elastic neutron scattering (QNS) study

Abstract

Abstract Quasi-elastic line broadening of neutrons scattered from 2at.%Co alloyed in β-Zr shows that at about 1100°C all Co atoms, not merely a small fraction, participate in fast diffusion of Co in Zr within a time interval of 10−9s. In the measured temperature range of 950 to 1380°C the deduced jump frequency is about 20 times faster than that of Zr in Zr-2 at.% Co but 8 times smaller than the Co jump frequency deduced from tracer measurements. This discrepancy, an anomalous decrease in intensity, and quasi-elastic neutron measurements at larger energy transfer indicate that a second jump frequency 30 times faster than the first one exists. From a comparison of all available experimental data it is inferred that the slower jump is either via vacancies between substitutional sites or a release jump from a trap, and it is concluded that the faster jump is between interstitial sites.