Sequence of phase transformations in metastable β Zr–12Nb alloy studied in situ by HEXRD and complementary techniques

Phase transformations in a metastable beta Zr–12Nb alloy were investigated by high-energy X-ray diffraction (HEXRD) measured simultaneously with thermal expansion situ during linear heating from room temperature to 800 °C. Complementary in-situ methods of electrical resistance and differential scanning calorimetry, which performed using the same conditions as HEXRD experiment, provided additional information on transformation sequence occurring alloy. Two bcc phases different lattice parameter, βZr βNb, observed range identified phase diagram Zr–Nb system. In initial solution-treated condition, athermal ω particles are present material. At about 300 °C, Nb-rich βNb starts form material original gradually disappears. Ex-situ observations microstructure transmission electron microscopy revealed cuboidal shape particles, is related relatively large misfit between β phases. 560 solvus was observed, an abrupt dissolution followed growth α phase.