Quenching defects in aluminum plus ten atomic per cent zinc

This study was undertaken to resolve the conflict which has recently arisen as to the as-quenched microstructure in the Al-Zn system as revealed by thin film transmission electron microscopy. The composition range of most active study has been that from 5 to 15 atomic per cent Zn in superpurity AL. Consequently a composition of 10 atomic per cent Zn was chosen for this study. There are no discontinuties in the phase diagram in this composition range which would influence the above choice. It exists as a single phase solid solution at high temperatures and as a two phase alloy at lower temperatures. The vast majority of previous studies has been carried out with ordinary air for an annealing or solution treating atmosphere and with distilled water for a quenching media, so this study has followed this previously established practice such that the results of this study will be generally applicable to the treatment of previously generated data. In many of these previous studies the actual microstructure was not determined, rather a microstructure was assumed from indirect evidence or taken from previous work and the data generated interpreted in light of this assumed microstructure --Preface, page iii