Enhancing mechanical performance of Ti₂ZrNbHfVAl_x refractory high-entropy alloys through laves phase

Refractory high-entropy alloys (RHEAs) have attracted significant interest because of their exceptional mechanical characteristics. This study examines the mechanical characteristics, microstructure and strengthening mechanism of Ti₂ZrNbHfVAl_x alloys (x = 0, 0.2, 0.4, 0.6, 0.8, 1, and 1.2). The results demonstrate that the introduction of Al causes a transformation in the phase structure of the alloys, resulting in the BCC phase and the Laves phase, characterized by a distinctive dendritic microstructure. The compressive yield strength is positively correlated with the rising Al content, while also resulting in a noticeable decrease in ductility due to the presence of the Laves phase. One of the alloys, the compressive yield strength of Ti₂ZrNbHfVAl_1.2 RHEA is as high as 1789.94 MPa, the compressive strain is 10.60 %, and the specific yield strength (SYS) of 269.67 kPa m³ kg⁻¹. Moreover, the Vickers hardness exhibits a rise from 317.29 to 533.73 HV. The high compressive yield strength mostly originates from solid solution and the second phase strengthening. The current investigation not only offers a resolution for attaining a harmonious combination of strength and ductility but also gives a valuable understanding of the advancement of RHEAs with exceptional mechanical characteristics.