Electron Beam Powder Bed Fusion of γ-Titanium Aluminide: Effect of Processing Parameters on Part Density, Surface Characteristics, and Aluminum Content

Metals

Frank Brückner¹  Lukas Stepien¹  Elena López¹  Mirko Teschke²  Marina Macias Barrientos²  Frank Walther²  Juliane Moritz³  Axel Marquardt³  Christoph Leyens³ 

[1] Department of Additive Manufacturing and Printing, Fraunhofer Institute for Material and Beam Technology IWS, 01277 Dresden, Germany;Department of Materials Test Engineering (WPT), TU Dortmund University, 44227 Dortmund, Germany;Institute of Materials Science (IfWW), Technische Universität Dresden, 01069 Dresden, Germany;

关键词: titanium aluminide;    additive manufacturing;    electron beam powder bed fusion;    electron beam melting;    process parameters;    surface roughness;   

DOI  :  10.3390/met11071093

来源: DOAJ

【 摘 要 】

Gamma titanium aluminides are very interesting for their use in high-performance applications such as aircraft engines due to their low density, high stiffness and favorable high-temperature properties. However, the pronounced brittleness of these intermetallic alloys is a major challenge for their processing through conventional fabrication methods. Additive manufacturing by means of electron beam powder bed fusion (EB-PBF) significantly improves the processability of titanium aluminides due to the high preheating temperatures and facilitates complex components. The objective of this study was to determine a suitable processing window for EB-PBF of the TNM-B1 alloy (Ti-43.5Al-4Nb-1Mo-0.1B), using an increased aluminum content in the powder raw material to compensate for evaporation losses during the process. Design of experiments was used to evaluate the effect of beam current, scan speed, focus offset, line offset and layer thickness on porosity. Top surface roughness was assessed through laser scanning confocal microscopy. Scanning electron microscopy, electron backscatter diffraction (EBSD) and energy-dispersive X-ray spectroscopy (EDX) were used for microstructural investigation and to analyze aluminum loss depending on the volumetric energy density used in EB-PBF. An optimized process parameter set for achieving part densities of 99.9% and smooth top surfaces was derived. The results regarding microstructures and aluminum evaporation suggest a solidification via the β-phase.

【 授权许可】

Unknown