Defects formed from excess vacancies in aluminum

Abstract
Three types of defects were observed in 99·999% aluminium after quenching from 540°c and ageing at 40°c to allow precipitation of excess vacancies: (1) hexagonal stacking-fault loops with Burgers vector ⅓, (2) rhombus-shaped perfect loops of Burgers vector ½ and (3) octahedral voids with {111} faces. The effect of quenching conditions on the type of defect formed was investigated. Stresses during quenching and the concomitant motion of dislocations were found to result in perfect ½ loops. Quenching conditions that minimized stresses were found to result in ⅓ stacking-fault loops or voids.
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