ȬɋɐɲȪયكᓺᅀᇋɀɳȻɓȪএệᇋΧǽḩᨕіኝ◧Iᭀং ነ̡ӟ̘ɿগDŽЈɿগ⛡ᥴᗁɿ۱ᨀ⇠ೢଉ ɿڤғʶଉ ଉ ኇɅʀጋك༔⓯ݨƗȤࢫ746-8501 ୮ۑ᭔ٷܦలϣ༔ᨊ 4560 ଉ ᴗ⒅შᗕ͆ᢼɿቦᄦᮾ᳣ᑿᐦቦᄦᮾ᳣ཀࢫ305-0047 ⇹᭔dzǞǿల٣ᥰ 1-2-1 ଉ ଉ ኇ̸গકগકрకકṾᮾ᳣ᲇἕ۰ᮾ᳣ᑿᐦࢫ113-8656 ኇ̸ȩᄙ̸ٚ೯᧯ 2-11-16The microstructure in 2.9 molಚ Y 2 O 3 -stabilized tetragonal zirconia polycrystal Y-TZP sintered at 1100c -1650c C was examined to clarify the role of Y 3ࢪ ions on the cubic-formation and grain growth processes. The cubic phase in Y-TZP stared to appear at 1300c C and the fraction of the cubic phase increased with the increasing sintering temperature. Scanning transmission electron microscopy and nanoprobe X-ray energy dispersive spectroscopy EDS measurements revealed that the Y 3ࢪ ion distribution in the grain interiors in Y-TZP was nearly homogeneous up to 1300c C and cubic phase regions in the grain interiors were formed clearly over 1300c C. The cubic phase region in the grain interior was extended as the sintering temperature increased. High-resolution electron microscopy and nanoprobe EDS measurements revealed that no amorphous layer existed along the grainboundary faces in Y-TZP, and Y 3ࢪ ions segregated at their grain boundaries over a width of ࣽ10 nm. The segregation peak of Y 3ࢪ ions was clearly seen at 1300c C, and above this temperature, Y 3ࢪ ions segregated at the grain boundaries not only between tetragonal grains but also between tetragonal and cubic grains. These results show that cubic phase regions started to be transformed from the grain boundaries andor the triple junctions in which Y 3ࢪ ions segregated. The cubic-formation mechanism in Y-TZP can be reasonably explained from the viewpoint of the Grain Boundary Segregation-Induced Phase Transformation model, and the grain-growth behavior is probably controlled by the solute drag effect of Y 3ࢪ ions segregating along the grain boundary.