Study of dispersoid particles in two Al–Mg–Si aluminium alloys and their effects on the recrystallization

An investigation has been done to study the effect of heat treatment on the formation and distribution of dispersoid particles in two AlMgSi alloys which contained the transition elements such as Zr and Mn, which have a low solubility in the α-aluminium solid solution and thus form dispersoids. The extrapolation technique of Cliff–Lorimer has been used to determine the chemical composition of dispersoid particles. The aim of this investigation was also to compare the effectiveness of Mn and Zr as dispersoid-forming elements in preventing the recrystallization. The incorporation of Si in the metastable Al3Zr type of dispersoid particles could increase the nucleation rate by reducing the volume free energy of formation of the dispersoid particles or decreasing the interfacial energy between the precipitate and the matrix. In these alloys, precipitation hardening occurs at higher temperatures than in conventional age-hardening aluminium alloys.