Intermetallic titanium aluminide (TiAl) alloys are considered attractive materials for high-temperature applications in aerospace, automotive, and energy industries. Additive manufacturing is a promising way of producing complex TiAl-alloy parts; however, it remains challenging due to brittleness of this alloy. While high-temperature preheating can mitigate cracking during selective laser melting, the microstructure of TiAl-alloys still needs to be optimized to achieve better mechanical performance. In this work, multiple laser exposures were used during selective laser melting of TiAl-based alloy to tailor its microstructure. Applying additional laser exposure of up to 20 times per layer induced an in situ heat treatment, which allowed to modify volume fraction and size of different phases. Microstructure, phase and chemical composition, and hardness of TiAl-alloys were investigsated with regards to several laser exposures during the selective laser melting process.

Titanium aluminide alloys are considered to be attractive materials for aerospace and automotive high-temperature applications due to their high specific strength, creep resistance, and heat resistance. However, their brittleness makes it difficult to manufacture complex-shaped components of these alloys using conventional processes making additive manufacturing a promising way to produce titanium aluminide parts. Additive manufacturing of titanium aluminide alloys involves high preheating temperatures affecting their microstructure; hence a proper heat treatment is needed to obtain desired properties. In this paper, a titanium aluminide alloy produced using Selective Laser Melting process with a high-temperature preheating was subjected to various heat treatments to study their effects on microstructure and properties of the alloy.

Additive Manufacturing (AM) is an attractive way of producing parts of intermetallic titanium alloys. However, high brittleness of these alloys makes it challenging to produce crack-free intermetallic parts by AM. One way to overcome this problem is to use high-temperature powder-bed preheating. In this paper, Ti-48Al-2Cr-2Nb alloy was obtained by selective laser melting process with high-temperature preheating of 800-900 ºC. Crack-free specimens with a relative density of 99.9% were fabricated using an optimized process parameter set. Microstructure and phase composition were studied using scanning electron microscopy and X-Ray diffraction to reveal a fine microstructure consisting of lamellar a2/? colonies, equiaxed ? grains, and retained ß phase. Compressive tests and microhardness measurements showed that the produced alloy exhibited superior properties compared to the conventionally obtained TiAl-alloy.

In this paper, laser powder-bed fusion (L-PBF) additive manufacturing (AM) with a high-temperature inductive platform preheating was used to fabricate intermetallic TiAl-alloy samples. The gas atomized (GA) and mechanically alloyed plasma spheroidized (MAPS) powders of the Ti-48Al-2Cr-2Nb (at. %) alloy were used as the feedstock material. The effects of L-PBF process parameters-platform preheating temperature-on the relative density, microstructure, phase composition, andmechanicalproperties ofprintedmaterialwere evaluated. Crack-free intermetallic samples with a high relative density of 99.9% were fabricated using 900 °C preheating temperature. Scanning electron microscopy and X-Ray diffraction analyses revealed a very fine microstructure consisting of lamellar α₂/γ colonies, equiaxed γ grains, and retained β phase. Compressive tests showed superior properties of AM material as compared to the conventional TiAl-alloy. However, increased oxygen content was detected inMAPS powder compared to GA powder (~1.1 wt. % and ~0.1 wt. %, respectively), which resulted in lower compressive strength and strain, but higher microhardness compared to the samples produced from GA powder.