No abstract

Pressureless sintering in air of a fine‐grained alumina–magnesia spinel (MgAl2O4) powder has been investigated using anisothermal and isothermal methods. Grain growth is controlled by the grain boundaries and densification is controlled by volume diffusion or grain‐boundary diffusion (no possibility to do a distinction). The apparent activation energies measured for grain growth and densification are 1100±50 and 915±50 kJ/mol, respectively. Grain boundaries and triple points have a different composition than the core of spinel grains. This could be the reason for the exceptionally high values of activation energies measured for grain growth and densification.