Tensile transformation-mismatch plasticity of bismuth sesquioxide

This study reports on experiments where bismuth sesquioxide (Bi₂O₃) was cycled between its high-temperature δ-phase and one or more of its low-temperature phases (α-, β-, or γ-Bi₂O₃) while being subjected to uniaxial tensile stresses in the range of 0.11-0.55 MPa. Reproducible strain increments of 0.4%-3.9% have been measured after each thermal cycle, and total tensile fracture strains of 10%-28% have been obtained using a combination of isothermal creep and transformation-mismatch plasticity. The strain due to transformation mismatch plasticity has been determined by two different methods and is proportional to the applied stress, which is quantitatively consistent with theoretical predictions for transformation superplasticity.