Influence of manufacturing processes on β-phase precipitates and corrosion properties of Zr-1Nb alloys

Zr-1Nb alloys manufactured by the alternate sequences between hot working and β-quenching were investigated in addition to an industry-fabricated Zr-1Nb material. Second phase particles, particularly composition and crystallography structure of β-phase precipitates, were characterized by electron microscopy. Pure steam corrosion test was performed to evaluate corrosion properties of the three Zr-1Nb alloys. Cross-sectional morphology and structure of the oxide films formed on the corroded alloys were analysed by scanning electron microscope and Raman spectroscopy. The results demonstrate strong effect of processing sequence on the β precipitates and corrosion properties. With the processing sequence of hot working and β-quenching, fine β-Nb particles are formed fully via precipitation from the Nb-supersaturated α-Zr grains, benefiting corrosion resistance. With the reverse sequence, the β phase and corrosion behavior are found dependent on hot working temperature in the phase regime of (α-Zr + β-Zr). Correlation between manufacturing processes and corrosion behavior is discussed in the light of second phase particles and oxides characterization.