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Transformation Plasticity and Toughening in CeO 2 ‐Partially‐Stabilized Zirconia–Alumina (Ce‐TZP/Al 2 O 3 ) Composites Doped with MnO
Author(s) -
Tsai JingFong,
Chon Uong,
Ramachandran N.,
Shetty Dinesh K.
Publication year - 1992
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.1151-2916.1992.tb05562.x
Subject(s) - materials science , composite material , fracture toughness , cubic zirconia , microstructure , phase (matter) , sintering , toughness , ceramic , chemistry , organic chemistry
Microstructure, phase stability, and mechanical properties of CeO 2 ‐partially‐stabilized zirconia (12 mol% Ce‐TZP) containing 10 wt% Al 2 O 3 and 1.5 wt% MnO were studied in relation to the base Ce‐TZP and the Ce‐TZP/Al 2 O 3 composite without MnO. The MnO reacted with both CeO 2 and Al 2 O 3 to form a new phase of approximate composition CeMnAl 11 O 19 . The reacted phase had a magnetoplumbite structure and formed elongated, needlelike crystals. The MnO‐doped Ce‐TZP/Al 2 O 3 composites sintered at an optimum temperature of 1550°C exhibited high strength (650 MPa in four‐point bending) and rising crack‐growth‐resistance behavior, with fracture toughness increasing from 7.6 to 10.3 MPa.In 12 in compact tension tests. These improved mechanical properties were associated with relatively high tetragonal‐to‐monoclinic transformation temperature ( M s =−42°C) at small grain size (2.5 μm), significant transformation plasticity in mechanical tests (bending, uniaxial tension, and uniaxial compression) and transformation zones at crack tips in compact tension specimens. The transformation yield stress, zone size, and fracture toughness were sensitive to the sintering temperature varied in the range 1500° to 1600°C. Analysis of the transformation zones using Raman microprobe spectroscopy and calculation of zone shielding for the observed zones indicated that a large fraction of the fracture toughness (∼70%) was derived from transformation toughening.