Defect clusters in heavy-ion irradiated nickel and nickel alloys

Low-dose (≲1012ions/cm2) heavy-ion irradiation gives a convenient method of studying some aspects of fast-neutron radiation damage and has now been studied using transmission electron microscopy in a wide variety of metals and alloys (e.g. see the reviews by Eyre 1973 and Wilkens 1975). From these studies a consistent picture of the development of the damage structure has emerged. In most cases small vacancy loops are observed, produced heterogeneously at the sites of displacement cascades by the collapse of vacancy-rich ‘depleted zones’. The interstitial component of the damage is usually lost to the foil surfaces and is not observed. There have been surprisingly few investigations of heavy-ion damage in materials of technological importance. However, it has been noted that cascade collapse appears to take place less readily in complex alloys such as steels than in pure metals such as copper (e.g. Williams and Eyre 1976) but few attempts have been reported to explore this effect systematically.