ON THE COMPETITION BETWEEN CONTINUOUS AND DISCONTINUOUS PRECIPITATIONS IN BINARY MG-AL ALLOYS

In Mg-Al, continuous precipitation is favoured at high and at low temperatures, whereas discontinuous precipitation dominates at intermediate temperatures. At high temperatures, discontinuous precipitation disappears both because volume diffusion prevents its growth and because its nucleation becomes difficult. At low temperatures continuous precipitation in the early stages of the heat treatment impedes the initiation of discontinuous precipitation.