[en] In 2Y-TZP powders calcined at temperature range of 800deg C to 1500deg C, the effect of stabilization and the transformability of tetragonal phase on the tetragonal to monoclinic transformation have been investigated. The transformability of tetragonal phase in calcined powders shows maximum at the calcination temperature of 1300deg C. This result is explained by a combined effect of the increase of particle size and of constrained force among the particle with increasing the calcination temperature. The amount of transformed monoclinic phase with calcination temperature after quenching in liquid nitrogen, stress induction and isothermal aging at 250deg C is also explained by the transformability of tetragonal phase determined by the sum of particle size effect and constraint effect. (Author)