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

Abstract

AbstractThe tetragonal to monoclinic martensitic transformation of plasma‐sprayed 3 mol% Y2O3–ZrO2 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 ct axis transforms to the am axis where (100)m//(001)t, (010)m, and (001)m//{110}t are clearly identified in addition to the correspondence where the ct axis transforms to the cm axis. Moreover, three growth modes are proposed and discussed according to strain accommodation. The observed sequential growth obeys the correspondence of the ct axis to the cm axis. Fourfold growth combines the correspondences of the ct axis to the cm and am axes. The interleaving growth follows the correspondences of the ct axis to the cm 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.