The kinetics of the discontinuous precipitation and dissolution in Mg-rich Al alloys

摘要

The morphology and growth kinetics of thediscontinuous precipitation and dissolution reactions insupersaturated Mg-Al solid solutions containing 7.3, 9.1 and 10.9at%Al have been investigated by optical and scanning electronmicroscopy and X-ray measurements. The volume fraction ofregions transformed by the discontinuous precipitation reaction,the reaction front velocity, the interlamellar spacing and theaverage composition of the solute-depleted lamellae weredetermined as a function of the temperature. For the first time, thekinetics of the discontinuous dissolution reaction has been studiedin the Mg-Al system. It has been shown that the transport of thesolute atoms during both reactions is governed by grain boundary diffusion.