Transmission Electron Microscopic Investigation on Recrystallization and Precipitation of Magnesium and Magnesium Alloys

Abstract

Experiments have been carried out to examine aging characteristics, recrystallization phenomena and effects of plastic deformation after water-quenching on the precipitation of Mg-Th alloys in the composition range from 1.7 to 4.0 w/t% thorium as compared with pure magnesium, Mg-Zn and Mg-Al alloys mainly with electron microscopic observations in thin foils. In Mg-4.0% Th alloys, G. P. zones were confirmed to exist before the appearance of the transition phase Mg2Th in accordance with the result of measurements of electrical resistance. The presence of thorium in a magnesium alloy greatly retarded such processes as recovery and recrystallization. This slowing up process seems to be reflected in the slow precipitation rate of Mg-Th compounds. The effects of cold working on precipitation in these alloys are not simple but complex.