Unravel the kinetics of eutectoid decomposition in additively manufactured Ti-8.5Cu alloy

Dynamic microstructural evolution is one of the key characteristics during laser additive manufacturing (LAM) due to its rapid thermal cycles. However, the change of microstructure due to solid-solid phase transformations is too fast to track using conventional characterization techniques. In situ synchrotron X-ray diffraction (XRD) delivers a unique solution to precisely describe the kinetics of phase transformations in a specific region, credited to its high frequency and high resolution of data collection. This study aims to unravel the phase transition pathway from martensite to ultra-fine pearlite during LAM of Ti-8.5Cu (wt%) alloy at beam line ID31. The onset temperature and time signature of eutectoid decomposition will be determined through the collected in situ XRD data. A range of laser processing conditions will be investigated to build up a complete database of cyclic phase transformations.