Order-disorder transformation in CuPd under 14.8 MeV neutron and 1.8 mev electron irradiations

Ordered and disordered CuPd samples were irradiated with fusion neutrons at RTNS-II to a fluence of −1.8×10 21 neutrons/m 2 at 4.3 K. The irradiation-induced resistivity increase in the ordered sample was about three times as high as that in the disordered one. A replacement to displacement ratio of 24 was obtained. Results of the isochronal annealing experiment show that the amount of recovery due to interstitial motion depends on the size difference factor in that a larger size difference prohibits interstitial reordering. Microscopy samples irradiated under similar conditions do not show any sign of disorder. Results from the 1.8 MeV electron irradiation at 100 K on an ordered CuPd sample give a replacement to displacement ratio of 3.1. Annealing this irradiated sample above 300 K resulted in a higher degree of long range order than that obtained prior to irradiation.