I. Energy calculations for pure metals

Abstract

The energies of voids, stacking-fault tetrahedra and vacancy loops in gold, silver, aluminium, copper, nickel, stainless steel, α-iron and molybdenum have been reexamined as a function of cluster size using established elastic continuum expressions. Stacking-fault tetrahedra and vacancy loops are the most stable small-cluster morphologies in all of the f.c.c. metals and in α-iron. The void is calculated to be the most stable small cluster in molybdenum. These results are in good agreement with recent experimental observations that have been made on high-purity metals. Once a void has nucleated and started to grow, it is very unlikely that it will collapse into a dislocation loop owing to the large energy barrier associated with the conversion process. The continuum calculations and experimental studies imply that impurities (such as gas) are necessary in order for void formation to be stable in most metals.