In situ transmission electron microscopy study of ion-irradiated copper: comparison of the temperature dependence of cascade collapse in fcc- and bcc-metals

The kinetics which drive cascade formation and subsequent collapse into poi nt-defect clusters are investigated by analyzing the microstructure produce d in situ by low fluence 100 keV Kr ion irradiations of fcc-Cu over a wide temperature range (18-873 K). The yield of collapsed point-defect clusters is demonstrated unequivocally to be temperature dependent, remaining approx imately constant up to lattice temperatures of 573 K and then abruptly decr easing with increasing temperature. This drop in yield is not caused by def ect loss during or following ion irradiation. In addition, this temperature dependence can be explained by a thermal spike effect. These in situ yield measurements are compared to previous ex situ yield measurements in fcc-Ni and bcc-Mo. (C) 2000 Elsevier Science B.V. All rights reserved.