Transformation-mismatch plasticity of NiAl/ZrO2 composites — experiments and continuum modeling

NiAl composites containing 10 and 20 vol.% unstabilized zirconia particles were thermally cycled around the polymorphic phase transformation range of zirconia while being subjected to an external uniaxial tensile stress. The strain rate of the composite during thermal cycling is significantly higher than the isothermal creep rate of either composite or unreinforced matrix at the same average temperature. An established model for transformation-mismatch plasticity of an allotropic, creeping metal has been adapted to describe the results. To the best of our knowledge, this is the first demonstration of transformation-mismatch plasticity in a composite induced through transformation of the minority-phase reinforcement.