Insights Into High‐Temperature Mechanical Properties and Oxidation Behavior of Ta‐Optimized TiAl‐Based Alloys Additively Manufactured via Directed Energy Deposition

Directed energy deposition (DED) is an effective method to process complex components with high efficiency, owing to its significant advantage of material saving and features of microarea metallurgy and rapid solidification. This study presents a nano‐Ta‐optimized Ti‐45Al‐8Nb (at%)‐based alloy synthesized via DED. The prepared TiAl‐based alloy exhibits homogeneously equiaxed grains, compared to the coarse columnar microstructure of pure TiAl alloys without Ta addition. The alloy optimized by Ta exhibits excellent ultimate tensile strength (UTS) at room temperature (950 MPa) and can still maintain a UTS of 751 MPa even at 800°C. Furthermore, the oxidation mass gain of the alloy after 200 h of isothermal oxidation at 850°C is only 0.31 mg cm −2 . Especially, the AlTa 2 formed during oxidation not only promotes the formation of dense Al 2 O 3 scales but also exhibits a certain coherent relationship with the Al 2 O 3 interface, effectively preventing oxidation and protecting the matrix. The Ta‐reinforced alloy helps guide the additive manufacturing (AM) of TiAl‐based alloys used at high temperatures (HTs), which feature controllable microstructures and enhanced mechanical properties.