DEFECT CLUSTERS IN ZN - A COMPUTER-SIMULATION STUDY

Calculations on point-defect clusters in Zn are performed using a stat ic simulation technique in conjunction with a many-body potential. The results are compared with the available experimental observations, th eoretical estimates and previous computations in hcp metals with cia r atios below the ideal value. Both monovacancy and divacancy defects de monstrate an anisotropic migration with almost the same activation ene rgy, corresponding to that observed in recovery stage IV. Small vacanc y clusters are found to favour three-dimensional agglomerates. Stabili ty conditions for vacancy clusters to nucleate or break up (recovery s tage V) are discussed. Small clusters of interstitials are shown to gr ow on the basal plane in forms based on the octahedral point defect, a lthough the most stable single interstitial is the nonbasal crowdion. Large single- and double-layer interstitial clusters are assigned to e mbryos of the experimentally observed dislocation loops.