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Low‐Temperature Superplasticity in Nanocrystalline Tetragonal Zirconia Polycrystal ( TZP )
Author(s) -
Yoshida Hidehiro,
Matsui Koji,
Ikuhara Yuichi
Publication year - 2012
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2012.05150.x
Subject(s) - materials science , nanocrystalline material , superplasticity , high resolution transmission electron microscopy , tetragonal crystal system , grain boundary , sintering , composite material , grain boundary sliding , amorphous solid , transmission electron microscopy , grain size , grain growth , atmospheric temperature range , cubic zirconia , mineralogy , microstructure , crystallography , ceramic , nanotechnology , crystal structure , chemistry , physics , meteorology
Nanocrystalline tetragonal ZrO 2 polycrystals ( TZP ) have been fabricated by the pressureless sintering of recently developed tetragonal ZrO 2 powder containing 5.69 mol% YO 1.5 and 0.60 mol% AlO 1.5 . The average grain sizes were 160 nm in the TZP sintered at 1150°C for 10 h and 150 nm in the 0.25 mol% GeO 2 ‐doped TZP sintered at 1100°C for 100 h. The TZP and Ge 4+ ‐doped TZP ‐sintered bodies were essentially single‐phase materials, and neither the amorphous layer nor the second‐phase particle was observed along the grain boundary faces. High‐resolution transmission electron microscopy ( HRTEM ), scanning transmission electron microscopy ( STEM ), and nanoprobe energy‐dispersive X‐ray spectrometer ( EDS ) measurements revealed that the Y 3+ , Al 3+ and Ge 4+ cations tend to segregate in the vicinity of the grain boundaries in the TZP ‐sintered bodies. The TZP and Ge 4+ ‐doped TZP exhibited an elongation to failure of more than 100% in the temperature range of 1150°C–1300°C and initial strain rate range of 1.4 × 10 −5 s −1 to 1.0 × 10 −2 s −1 . For instance, an elongation to failure in the Ge ‐doped TZP reached about 200% at 1150°C and 1.4 × 10 −5 s −1 . The nanocrystallization reduced the lower limit of the superplastic temperature of conventional, submicron‐grain TZP materials by 150°C. The improved ductility of the TZP at low temperatures was essentially attributed to the reduced grain size.