Abstract
The temperature dependence of the Vickers microhardness was studied in 3.4-mol%-Y2O3-partially-stabilized ZrO2 (Y-PSZ) single crystals up to 1000°C; the samples had previously been annealed at 1600°C for 150 h to develop “colony” precipitates of tetragonal ZrO2 in the cubic ZrO2 matrix. Indentation caused extensive stress-induced martensitic transformation of the colony precipitates to monoclinic symmetry in zones which extended in extreme cases up to several hundred micrometers from the indent. For indents made at 500°C and above, the Md and Mf temperatures are 450° and 310°C, respectively; As is ∼600°C (Md is the temperature of initial transformation (the “martensite start temperature”) in deformed samples; Mf is the temperature at which the final transformation occurs; As is the temperature at which the reverse (monoclinic → tetragonal) transformation begins). However, extensive transformation zones are also found for indents made at 200°, 300°, and 400°C. The dislocation density introduced during indentation is responsible for nucleating the transformation in a zone adjacent to the indent. However, the transformation zone extends further than the plastic zone around the indent, indicating extensive autocatalytic transformation. Transformation within the zone appeared to occur in individual plates with {110} habit planes. The plate dimensions (∼100 μm ×∼175 μm ×∼10 μm) are large compared to the size of the colony precipitates (∼2 μm in maximum dimension).
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call