Growth modes for monoclinic yttria‐stabilized zirconia during the martensitic transformation

Abstract

The tetragonal to monoclinic martensitic transformation of plasma-sprayed 3 mol % Y 2 O 3 -ZrO 2 coatings is investigated by electron backscatter diffraction. The original metastable tetragonal phase shows an approximate "basal" texture with {001} t parallel to the coating surface. Based on the orientation analysis, plenty of monoclinic variants with atypical correspondence which indicates the c t axis transforms to the a m axis where (100) m //(001) t , (010) m , and (001) m //{110} t are clearly identified in addition to the correspondence where the c t axis transforms to the c m axis. Moreover, three growth modes are proposed and discussed according to strain accommodation. The observed sequential growth obeys the correspondence of the c t axis to the c m axis. Fourfold growth combines the correspondences of the c t axis to the c m and a m axes. The interleaving growth follows the correspondences of the c t axis to the c m axis within three tetragonal domains. These phenomena demonstrate the typical twin-related and self-accommodating configuration, which is in agreement with the phenomenological theory. These finding provide fundamental insight into the martensitic transformation mechanism and demonstrate a route for increasing the lifetime by controlling the tetragonal to monoclinic phase transformation. K E Y W O R D S electron backscatter diffraction, martensitic transformation, orientation relationship, yttria-stabilized zirconia

Tetragonal reconstruction and monoclinic variants rearrangement during heat treatment in zirconia

“…Recently, as we confirmed in an earlier work 14 based on electron‐backscattered diffraction (EBSD) high‐resolution data, the correspondence A as well as an atypical A could also be formed in plasma‐sprayed zirconia coatings. However, to identify the accurate correspondence of monoclinic variants, the orientation of prior tetragonal crystal was necessary.…”

Effect of Microstructure on the Thermal Conductivity of Plasma Sprayed Y2O3 Stabilized Zirconia (8% YSZ)

“…Some of monoclinic phase grains were fine. This can be explained by the fact that t to m phase transformation usually occurs partly inside larger primary t grains, with the fine m-grains being subsequently developed [25]. The grain boundary density was inversely related to the grain size.…”

Effect of La2O3 on Microstructure and Thermal Conductivity of La2O3-Doped YSZ Coatings

“…However, very few reports mentioned the influence of La 3+ on crystal structures, such as grain size. Furthermore, for YSZ coatings, the effect of microstructure on the thermal conductivity has been studied extensively using the electron back-scattered diffraction (EBSD) method, but there are almost no reports regarding the effect of microstructures on the thermal conductivity of La-YSZ by EBSD method [17,18,19].…”