Study of the ferroelastic transformation in zirconia by neutron diffraction

Abstract

Neutron diffraction studies of tetragonal zirconia polycrystals subjected to various applied uniaxial stresses indicate that a ferroelastic crystalline transformation occurs within the bulk of the material. The critical coercive stress is determined to be 1.65 ± 0.03 GPa. The results agree well with previous reports concerning the ferroelasticity of tetragonal zirconia, but they are the first direct evidence indicating that the anomalies observed using the first X-ray diffraction studies originate from the bulk of the ceramic and not solely from the surface. The preferred orientation observed in the tetragonal crystallites was measured as a function of applied uniaxial stress and interpreted via a resolved stress criterion. It is believed that the ferroelastic transformation can act as an energy-absorbing mechanism and hence toughen zirconia or ceramics containing dispersed zirconia.