Effects of Neutron Irradiation on Some Superplastic Characteristics of Tetragonal Zirconia Polycrystals Containing 3 mol% Yttria

Abstract

Fast neutrons (energy > 1.6 × 10⁻¹³ J) were irradiated to tetragonal zirconia polycrystals containing 3 mol% yttria (3Y-TZP) at the fluence levels of 2.5 × 10²⁴ (Light irradiation) and 4.3 × 10²⁴ (Heavy irradiation) m⁻². The irradiation caused no significant swelling in the 3Y-TZP specimens. After the neutron irradiation, superplastic characteristics were examined by tensile tests at a temperature range from 1623 to 1773 K with initial strain rates ranging from 5.0 × 10⁻⁴ to 1.67 × 10⁻² s⁻¹. It was found that the elongation to fracture of the irradiated specimens was quite small in comparison with that of unirradiated ones. The apparent activation energy for the superplastic flow of the irradiated 3Y-TZP was fairly high, i.e. 785 ± 35 and 693 ± 26 kJ·mol⁻¹ for Light and Heavy irradiations, respectively. It appears that the induced defects, nuclear transmutation and radiation-induced segregation in the 3Y-TZP due to the neutron irradiation are responsible for these property changes.