Effect of an applied electric field on the flow stress of ultrafine-grained 2.5Y-TZP at high temperatures

It was concluded that the rate-controlling mechanism in the present tests is grain boundary sliding accommodated by lattice diffusion of the Zr ions with a threshold stress σo, giving an acting effective stress σe = σ − σo. It was determined for this case that ΔσE* contained reductions in both the effective stress (Δσe,E*) and in the threshold stress (Δσo,E). Analysis of the behavior in terms of an electrochemical potential for vacancy formation showed that Δσe,E* and Δσo,E are related to changes in the electric field potential pertaining to the space charge at the grain boundaries. The calculated width of the space charge region acted on by the electric field was 3-5 nm in the temperature range of 1450-1550 °C.