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Influence of Amorphous Grain Boundary Phases on the Superplastic Behavior of 3‐mol%‐Yttria‐Stabilized Tetragonal Zirconia Polycrystals (3Y‐TZP)
Author(s) -
Gust Maria,
Goo Grace,
Wolfenstine Jeff,
Mecartney Martha L.
Publication year - 1993
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.1151-2916.1993.tb06635.x
Subject(s) - superplasticity , materials science , strain rate , grain boundary , grain boundary sliding , composite material , grain boundary diffusion coefficient , fracture toughness , amorphous solid , activation energy , deformation mechanism , phase (matter) , sintering , metallurgy , crystallography , microstructure , chemistry , organic chemistry
Amorphous silicate grain boundary phases of varying chemistry and amounts were added to 3Y‐TZP in order to determine their influence on the superplastic behavior between 1200° and 1300°C and on the room‐temperature mechanical properties. Strain rate enhancement at high temperatures was observed in 3Y‐TZP containing a glassy grain boundary phase, even with as little as 0.1 wt% glass. Strain rate enhancement was greatest in 3Y‐TZP with 5 wt% glass, but the room‐temperature hardness, elastic modulus, and fracture toughness were degraded. The addition of glassy grain boundary phases did not significantly affect the stress exponent of 3Y‐TZP, but did lower the activation energy for superplastic flow. Strain rate enhancement was highest in samples containing the grain boundary phase with the highest solubility for Y 2 O 3 and ZrO 2 , but the strain rate did not scale inversely with the viscosity of the silicate phases. Grain boundary sliding accommodated by diffusional creep controlled by an interface reaction is proposed as the mechanism for superplastic deformation in 3Y‐TZP with and without glassy grain boundary phases.