Twinning-induced plasticity (TWIP) effect in multi-phase metastable beta Zr-Nb alloys

The deformation mechanisms were studied in metastable Zr-13.8Nb-0.7Hf and Zr-15.5Nb-0.7Hf (wt.%) alloys exhibiting complex microstructures due to quenched-in precipitates (acicular body-centered tetragonal phase and globular monoclinic phase) in beta grains. Twinning-induced plasticity (TWIP) effect was observed in Zr-13.8Nb-0.7Hf via {332}<113> twinning operation, resulting in higher strain-hardening rate and uniform elongation than those of Zr-15.5Nb-0.7Hf deforming via only dislocation glide. In-situ characterizations, by applying tensile deformation during electron backscattered diffraction (EBSD) mapping and transmission electron microscopy (TEM) observation, were conducted to clarify the twinning process and the role of quenched-in precipitates when interacting with deformation twins.