Effect of an Alternating Current Electric Field on the Plastic Deformation of Ultrafine-Grained 3Y-TZP at 1400 °C and 1500 °C

The influence of a 60 Hz alternating current (ac) electric field E _rms = 6.7 to 7.5 V/cm applied in the loading direction on the flow stress of 3 mol pct yittria-stabilized tetragonal zirconia polycrystals (3Y-TZPs) in uniaxial tension at 1400 °C and 1500 °C was determined. Two test types were performed: type a, where the field was applied continuously throughout the tension test; and type b, where the field was alternately applied and removed. The field reduced the flow stress in both test types but with an appreciably greater effect in type a. The reduction in flow stress in the type b tests was regained upon removal of the field and was attributed to a decrease in the energy to form the rate-controlling Zr⁴⁺ vacancies in the space charge zone adjacent to the grain boundaries. The larger reduction in flow stress in the type a tests was attributed to a retardation of grain growth by the field as a result of a decrease in the driving force. The results obtained with the ac field were in agreement with those with direct current (dc) field.