In situ characterizations of phase transformations kinetics in the Ti17 titanium alloy by electrical resistivity and high temperature synchrotron X-ray diffraction

The β(BCC)→α(HCP)+β(BCC) phase transformation kinetics of the β-metastable titanium alloy Ti17 was studied by in situ high energy X-ray diffraction (XRD) and electrical resistivity. The use of synchrotron radiation (E=89.12E=89.12 keV, λ=0.01402λ=0.01402 nm) allowed to characterize specimens 6 mm in diameter, limiting thus oxidation effects. The α+β→β phase transformation kinetics was characterized during continuous heating up to the β temperature range. The β→α+β transformation was studied in isothermal conditions (dwell at 708 °°C or 750 °°C) and during continuous cooling (cooling rates of 0.05 °°C/s, 0.1 °°C/s and 0.61 °°C/s). The evolutions of the phase fractions are analyzed and compared to kinetics measured by electrical resistivity, showing a good correlation between both methods. In addition, the evolutions of the cell parameters of each phase obtained from XRD patterns are analyzed in regard of the transformation kinetics.