The study of martensitic transformation and nanoscale surface relief in zirconia

摘要

Fine ceramics materials have entered into the industry application and partially stabilized zirconia (PSZ) is a typical example among them. PSZ has outstanding mechanical properties with other ceramics, such as high bending strength and high fracture toughness. These good properties will be mostly dependent on the phase transformation form the metastable tetragonal (t) to the stabler monoclinic (m) phases. In ZrO_2, energy is expended during tetragonal (t) to monoclinic (m), and this energy expended can relieve the stress concentration at the crack tip, on the other hand, about 5% of volume expansion during (t) to (m) of transformation produces a compression zone at the crack tip, and it can stop the crack propagation, so that fracture toughness can be increased. Much research has been done for the mechanism of phase transformation and toughening of tetragonal (1) to monoclinic (m) [1-5], However, it can not do to measure the size of transformation products quantitatively due to the limited equipiments, especially to measure its nanoscale height of martensite plates, and it is worthwhile to do this work in more detail.