Lattice deffects in well annealed aluminum revealed by X-Ray topography

Abstract

Aluminum crystals of considerably low dislocation density were obtained through simple isothermal annealing followed by furnace cooling of single crystals grown from the melt. Characterization of lattice defects was made by means of X-ray diffraction topography at room temperature. Most of the dots are revealed to have no single Burgers vector of <110> or <111> type. They probably are dislocations and/or vacancy clusters bound to impurities. It seems that, in a macroscopic scale, some of the rows of prismatic dislocation loops are developed from helical dislocations and others are punched out from certain point sources. The difference in dislocation configuration between the two cases, annealed in air and in vacuum, is attributed to the difference in the nature of oxide layer.