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 temp eratures, whereas discontinuous precipitation dominates at intermediat e temperatures. At high temperatures, discontinuous precipitation disa ppears both because volume diffusion prevents its growth and because i ts nucleation becomes difficult. At low temperatures continuous precip itation in the early stages of the heat treatment impedes the initiati on of discontinuous precipitation.