Abstract

High temperature plastic flow or grain boundary failure in oxide ceramics such as Al2O3 and tetragonal ZrO2 polycrystal (TZP) is sensitive to small levels of doping by various cations. For example, high temperature creep deformation in fine-grained, polycrystalline Al2O3 is highly suppressed by 0.1 mol% lanthanoid oxide or ZrO2-doping. An elongation to failure in superplastic TZP is improved by 0.2–3 mol% GeO2-doping. A high-resolution transmission electron microscopy (HRTEM) observation and an energy-dispersive X-ray spectroscopy (EDS) analysis revealed that the dopant cations tend to segregate along the grain boundaries in Al2O3 and TZP. The dopant effect is attributed to change in the grain boundary diffusivity due to the grain boundary segregation of the dopant cations. A molecular orbital calculation suggests that ionicity is one of the most important parameters to determine the high temperature flow stress, and probably, the grain boundary diffusivity in the oxide ceramics.

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

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.