Additive manufacturing of TiAl-based alloys

Abstract

The ever-increasing demand for developing lightweight, high-temperature materials that can operate at elevated temperatures is still a subject of worldwide research and TiAl-based alloys have come to the fore. The conventional methods of manufacturing have been used successfully to manufacture the TiAl-based alloy. However, due to the inherent limitations of the conventional methods to produce large TiAl components with intricate near-net shapes has limit the widespread application and efficiency of the TiAl components produced using conventional methods. Metal additive manufacturing such as Electron Beam Melting technology could manufacture the TiAl alloys with intricate shapes but lack geometrical accuracy. Laser powder bed fusion (LPBF) technology could manufacture the TiAl-based alloys with intricate shapes with geometrical accuracy. However, the inherent high rate of heating and cooling mechanisms of the LPBF process failed to produce crack-free TiAl components. Various preheating techniques have been experimented, to reduce the high thermal gradient and residual stress during the LPBF process that causes the cracking of the TiAl components. Although these techniques have not reached industrial readiness up to now, encouraging results have been achieved.

Additive Manufacturing of Ti-Based Intermetallic Alloys: A Review and Conceptualization of a Next-Generation Machine

“…Since the performance of a material does not depend only on its mechanical properties but also on its geometrical configurations [12,28,40], using the emerging AM manufacturing technology to produce the two-phase γ(TiAl) + α 2 (Ti 3 Al) Ti-(44-49)Al alloy with near-net shapes would certainly improve its technical and functional performance.…”

“…Due to the complex geometry of the final 3D components, post-processing activities become very complicated [12]. Trying to machine the EBM manufactured components to the final precise dimensions would also result in waste of the material, which undermines one of the main benefits of PBF manufacturing technology to save material [29].…”

“…The decline of interest in Materials 2021, 14, 4317 2 of 15 NiAl-based alloys was exacerbated by their extremely low plasticity. Although the work of Aoki and Izumi [10] and the collaborative research project of ORNL [4] seemed to resolve the low plasticity problem of NiAl-based alloys with the addition of boron, TiAl-based alloys seem to take the center stage and have attracted much more research interest and commercialization than NiAl and FeAl-based intermetallic alloys [11,12].…”

“…Some intermetallic alloys maintain the ordered crystal lattice up to their melting points [1,14,15]. It is the ordered structural characteristics that make intermetallic alloys a prime choice for high-temperature applications [12]. The main properties of intermetallic alloys can be summarized as follows: high melting points, high thermal conductivity, low densities, good strength, good structural stability particularly at high temperatures, good oxidation, good wear, and good corrosion resistance at high temperatures due to the continuous formation of an adherent alumina surface layer [1,3,5,8,11].…”

“…AM technology could be used to produced three-dimensional (3D) printed parts with intricate geometrical configurations [31]. It is considered a monolithic manufacturing process that gives the manufacturing engineer freedom of design to produce near-net shapes for tailored engineering applications [12,28]. The unique capabilities of AM manufacturing technology for producing near-net shapes of complex geometries for tailored applications have triggered intensive academic and industrial research on manufacturing TiAl-based intermetallic alloys with intricate geometries via AM technology.…”