Abstract
This study aims to obtain understanding of the microstructural evolution (recovery and decomposition of martensite α’ during post heat treatment in the Ti-6Al-4V alloy manufactured by laser powder bed fusion (L-PBF). The microstructural evolution was tracked using synchrotron radiation facilities. In addition, interrupted heating at different temperatures was conducted to observe the microstructural evolution during heating by Scanning Electron Microscopy and Transmission Electron Microscopy (TEM). The phase fractions, the mean lattice parameters and the Full width at half maximum (FWHM) variations were determined by Rietveld refinement from XRD patterns during continuous heating from room temperature up to the single β-phase domain. The complementarity of characterization tools clearly evidenced that the decomposition of the alpha’ martensite resulted in a noticeable modification of its mechanical state and a progressive change of its chemical composition, leading to the characteristics of the phase. In addition, the change in the chemical composition of alpha' martensite during heating leads to the formation of the alpha phase at the interface alpha’/alpha’ and on the internal twinning by a diffusional mechanism