Self-interstitial Clusters Research Articles

An investigation of the mobility of vacancies and interstitials in a Ag,-9 at. % Zn alloy by means of high-voltage electron microscopy

Abstract The characteristics of vacancy and self-interstitial clustering behaviour have been studied in a Ag-9 at. ′% Zn alloy during irradiation in an electron microscope operated at 800 or 1000 keV in the temperature range between 250 and 410 K. The salient feature of the observations was that, for irradiation temperatures below 300 K, only stacking-fault tetrahedra were nucleated while, for irradiations above 360 K, all defect agglomerates were faulted dislocation loops of interstitial type. Deeper insight into the mobility of point defects was gained by the realization of two-step irradiations. These have shown that preformed interstitial loops shrank during subsequent re-irradiation below 300 K. This demonstrates, using conventional methods of analysis for the dynamics of the defect populations associated with a fast particle flux, that vacancies migrate faster than selfinterstitials at low temperatures. The present evidence for this unique behaviour of elementary defects in a metal lattice is in agreement with previous anelasticity results obtained in other concentrated AgZn alloys, in which the single vacancy has been identified to be the faster moving defect.

Stress-induced ordering of self-interstitial clusters in Al and Cu

Although there have been made many calculations for structures of the self-interstitial in Si and small aggregates of interstitials, In, there have been relatively few attempts to relate these defects with experimental data. Here, we discuss the assignments of the self-interstitial to the AA12 EPR centre and the di-interstitial to the P6 EPR centre.

Characterization of Point Defect Clusters by 2-1/2-D TEM

Many of the TEM studies of radiation damage in crystalline materials have been directed toward illucidating the nature, number density, and size distributions of the primary structural defects resulting from the displacement of atoms from their normal lattice sites, i.e., "black spots." The "black spots" have been identified as either nonresolvable dislocation loops or planar clusters of self interstitials or vacancies by TEM techniques and diffraction contrast theories that are described in the book by Hirsch, et al. and the reviews by Ruhle and Eyre. An indispensable part of the studies of point defect clusters is the identification of their character (vacancy or interstitial).