Precipitation and sintering behaviour of non-stoichiometric MgAl₂O₄ solid solution powder prepared by combustion synthesis

In this work, non-stoichiometric MgAl₂O₄ spinel solid solution powders with excess magnesia or alumina were synthesized by combustion synthesis, and their precipitation and sintering behaviour were investigated. The dissolution of MgO or Al₂O₃ in the lattice of spinel formed interstitial or vacancy solid solutions, respectively. During annealing, the powders with different solid solubility exhibited various precipitation and phase transition behaviour. After hot-press sintering with the as-prepared powders, there were many spheres with 100 nm evenly precipitated in the MgAl₂O₄ ceramic matrix, which improved mechanical performance. This work can not only provide comprehensive information about the precipitation of magnesia- and alumina-rich MgAl₂O₄ spinel solid solutions during annealing or sintering, but also offer an easy and convenient way for the industrial preparation of nanocomposite MgAl₂O₄ ceramics.