In this study the feasibility to process a γ-TiAl alloy using a composite extrusion modeling (CEM) process was tested.
The achieved material properties are compared with those of materials manufactured using the metal injection molding (MIM) process. The advantage of the CEM process is that it can use the existing technical infrastructure of the established MIM process route. The CEM process combines this with the advantages of additive manufacturing processes, such as high geometrical degrees of freedom, optimized use of materials and the possibility to produce small batch sizes economically because no invest in expensive tooling needs to be amortized. This reduces material and machine costs. Furthermore, process-related residual stresses and their negative effects on component properties are negligible compared to powder bed-based additive manufacturing processes such as laser or electron beam melting.
The first step of the process was to fabricate spherical TNM alloy powder (Ti-43.5Al-4Nb-1Mo-0.1B, at.%) using the electrode induction inert gas atomization method (EIGA-process) at the Helmholtz Center hereon. After sieving, the powder fraction below 25 μm was used to produce a paraffin-based binder feedstock. The starting material was then granulated into particles with a diameter of 1–3 mm and dog bone-shaped samples were prepared using an AIM3D ExAM 255 printer for CEM processing and an Arburg 370A injection molding machine for MIM processing.
All fabricated samples were thermochemically debinded and sintered in an inert argon gas atmosphere. The obtained microstructure and phases were analyzed using SEM and EBSD as well as high-energy X-ray diffraction.
For both CEM and MIM fabrication techniques, tensile tests were performed at room temperature. Additionally, compression creep tests were performed at two different temperatures, 700 °C and 800 °C, under a load of 150 MPa.