Plastic deformation of fine-grained Al 2O 3 in the presence of an electric field

Abstract

Although polycrystalline ceramics are generally considered to be brittle, they can exhibit significant ductility at high homologous temperatures for certain conditions, namely a fine grain size (usually {le} 5 {micro}m) and non-stoichiometry. Prior studies by the present authors have shown that the concurrent application of an electric field of {approximately} 1 kV/cm during the tensile deformation of polycrystalline NaCl and 3Y-TZP (yttria-stabilized tetragonal zirconia polycrystals) gave a reduction in the flow stress and an increase in elongation. The present investigation was undertaken to determine the influence of an electric field on the plastic deformation of a fine-grained, polycrystalline Al{sub 2}O{sub 3}, which is normally considered to be highly stoichiometric. The objectives of the study were to determine: (a) the influence of a continuous electric field on the tensile stress-strain curve, (b) the degree of reversibility of any effect of the field on the flow stress and (c) the dependence of the flow stress on the field strength.