Measurement of phase transformation kinetics during repeated thermal cycling of TI-6AL-4V using time-resolved X-ray diffraction

An understanding of the microstructural evolution in a Ti-6Al-4V alloy during laser processing is complicated by the repeated thermal cycling above and below the β↔α+β phase boundary. A synchrotron radiation time-resolved X-ray diffraction technique was used to track the phase transformation kinetics of αa+β to βduring heating and β to α+β during cooling, for multiple thermal cycles. The measurements showed that the transformation during heating closely followed the equilibrium phase diagram. The experimental results are compared with a microstructure model based on computational thermodynamics and kinetic calculations.