Superplatic behavior in GeO{sub}2 or TiO{sub}2 doped and Ge-Ti co-doped 3mol% yttria doped tetragonal zirconia polycrystals (TZP) are examined under a uniaxial tension in air at 1400°C and an initial strain rate of 1.3 × 10{sup}(-4)s{sup}(-1). Diffsivity on static grain growth behavior is enhanced by Ge-Ti co-doping. Dependence of the flow stress on the amount of co-doped Ge-Ti is close to that in Ge doped TZP, but much lower than that in Ti-doped TZP. The elongation to failure is highly improved by the co-doping in comparison with Ge or Ti doping. The largest nominal strain of 988% was obtained in 2mol%GeO{sub}2-2mol%TiO{sub}2 co-doped TZP.
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