13. Creep in MgO

MgO and MgO composite (MgO·Al₂O₃) are discussed in this chapter. The value of the stress exponent determined as n = 3.3 suggests a dislocation model as the rate-controlling creep mechanism. In the absence of glide the dislocation motion is that of climb, which is the rate-controlling mechanism. Knowledge of the structure is of great importance for understanding the creep deformation mechanism in the power law range. It is revealed that the typical dislocation structure of creep-deformed MgO is qualitatively very similar to that of creep-deformed metals and that the grains are divided into well-defined subgrains. Creep in polycrystalline and single-crystal MgO are considered in this chapter and the experiments were performed by tensile, compressive and flexural tests. Creep rupture, superplasticity, and nano-MgO are important sections of this chapter.