Precipitation simulations of the O-phase in Ti2AlNb alloys synthesized by laser powder bed fusion

Abstract

Ti2AlNb alloys based on the ordered orthorhombic (O) phase are structural high temperature candidate materials for weight reduction in engines and aircraft. Their complex microstructure is strongly dependent on the processing conditions challenging their development for practical applications. Efforts in the last decades have been made to improve their mechanical properties by correlating the effect of different processing conditions and final microstructures [1]. In the last years Ti-22Al-25Nb alloy has received attention due to its processability by additive manufacturing. We investigate the precipitation of the Ophase in Ti-22Al-25Nb alloys during an annealing step of 3 h at 600 °C. Samples were printed by Laser Powder Bed Fusion (LPBF) with low baseplate pre-heating temperatures. The microstructure of the alloys was investigated before and after the annealing step using electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS) for the chemical analysis. The phase fractions during precipitation were measured by highenergy synchrotron X-ray diffraction (HEXRD) at the beamline P07-HEMS of the PETRA III source (Deutsches Elektronen-Synchrotron, DESY) in Hamburg, Germany. Precipitation simulations were done using the ThermoCalc PRISMA module in combination with welldeveloped thermodynamic and mobility databases TCTI/Ti-alloys version 3 [2].

References [1] Zhang H., et al., J. Mater. Sci. Technol., 80 (2021): 203. [2] Thermo-Calc Software Package PRISMA module 2023b and Ti/TiAl-based Alloys database version 3. [3] Sadi F.A. and Servant C., Mater. Sci. Eng. A, 346 (2003) 19. [4] Ansys Optislang. https://www.ansys.com/products/connect/ansys-optislang