Superplasticity of Yttria-Stabilized Tetragonal ZrO₂Polycrystals

Abstract

The uniaxial tensile deformation behavior of 3 molpercent Y/sub 2/O/sub 3/-tetragonal ZrO/sub 2/ polycrystals was studied at temperatures up to 1500 C in ambient atmosphere. The tensile specimens which were elongated at constant displacement rates from 0.00011/s to 0.00055/s at 1450 C exhibited unusually large deformation. The superplastically deformed specimens retained a bending strength of 976 MPa at room temperature. Steady creep rates measured at a constant load in the range of relatively small strains were described by a stress component, n, of 2 and by an activation energy of 586 + or - 40 kJ/mol. Large deformations during the accelerating creep were accompanied by extensive formation of cavities. 19 references.