Enhanced mechanical properties of tantalum alloys via multi-principal elements and compositionally complex carbides

Tantalum (Ta) alloys have been widely utilized in rocket, air-breathing engines, and airframe applications. However, traditional Ta alloys suffer from insufficient strength at ultra-high temperature, making it challenging to satisfy the design requirements for next-generation aerospace equipment. We report a novel strategy to design Ta alloys with superior mechanical properties by integrating the multi-principal element concept with compositionally complex carbides. By introducing multiple refractory elements and C, the resultant alloys displayed a thermally stable microstructure consisting of two phases. With the increasing C contents, the microstructure evolved from hypoeutectic to eutectic and then to hypereutectic. These varying microstructural characteristics influenced crack blunting and dislocation accumulation behaviors, leading to different softening resistance at 1600 °C and plasticity at room temperature. Benefiting from the strengthening effects of solid solution and compositionally complex carbides, these alloys exhibited a high strength of ~600 MPa at 1600 °C, significantly superior than that of traditional Ta alloys.