Explanation

The martensitic phase transformation from tetragonal zirconia (t-ZrO2) to monoclinic zirconia (tn-ZrO2) is used to improve the mechanical properties of brittle ceramics and make them from brittle to tough. In the ceramic matrix, small ZrO2 particles are dispersed in its crystal structure. Under the action of external force, cracks in ceramics begin to initiate and propagate. Near the crack tip, a martensitic phase transformation from t-ZrO2 to tn-ZrO2 occurs. This phase transformation is accompanied by volume expansion and shear, forming a stress field. This stress field interacts with the stress field at the crack tip, thus changing the local stress intensity factor. In this case, in order to make the crack continue to propagate, the external force needs to be increased, which will lead to transformation toughening. This means that the external force will promote the phase transformation, leading to the change of crystal structure, thus absorbing the external force and delaying the propagation of cracks. This mechanism increases the toughness of materials, makes them more resistant to cracking and fracture, and improves the mechanical properties of ceramics materials. The application of this martensitic phase transformation phenomenon helps to develop more durable ceramics materials, which are widely used in high-temperature applications and structural engineering to meet strict performance requirements.

Classification