Structure and mechanical properties of ambient ductile TiZrNbHf refractory high-entropy alloy: A first principles and experimental study

Refractory high-entropy alloys (RHEAs) are known for their high structural stability and excellent mechanical properties, making them promising candidates for various applications. However, many RHEAs exhibit poor plasticity and processability. In this study, we successfully prepared a TiZrNbHf alloy with a uniform composition and investigated its phase stability, microstructure, and tensile properties. Our main findings reveal that TiZrNbHf alloys demonstrate excellent cold-rolling properties, exhibiting no cracks at rolling deflections of up to 80 %. Additionally, the alloy shows good cold working performance and a pronounced work hardening effect, with a yield strength of 677 MPa in the heat-treated state and 1116 MPa in the rolled state. The tensile fracture strain in the heat-treated state exceeds 27 %. Notably, the TiZrNbHf alloy maintains phase stability, showing no phase transformations during cold rolling or heat treatment. Furthermore, we utilized first-principles calculations based on density functional theory (DFT) to examine the alloy's elastic properties, anisotropy, lattice distortion effects, and electronic structure. These calculations provide valuable insights into the mechanical behavior of TiZrNbHf alloys at the atomic scale, complementing experimental findings and enabling the determination of mechanical parameters that are difficult to obtain experimentally. In summary, this work investigates the microstructure and mechanical behavior of TiZrNbHf alloy across multiple scales, offering a reference for the design of new ductile RHEAs.