Microstructure and properties of Al0.5NbTi3VxZr2 refractory high entropy alloys combined with high strength and ductility

Abstract

Novel lightweight Al0.5NbTi3VxZr2 (x = 0.5, 1.0, 1.5) refractory high entropy alloys were synthesized by vacuum arc melting. The microstructure evolution and mechanical properties of Al0.5NbTi3VxZr2 alloys were analyzed. All Al0.5NbTi3VxZr2 alloys have a single BCC structure, and the addition of V does not change the microstructure of the alloys. At elevated temperatures, V1.0 alloy shows good phase stability, and the compressive yield strength of V1.0 alloy is 898 MPa at room temperature, 706 MPa at 873 K, and 110 MPa at 1073 K, respectively. Al0.5NbTi3VxZr2 alloys reveal excellent compression deformability, all samples can be compressed to more than 50% strain at room and elevated temperatures without fracture. At room temperature, V1.0 alloy still possesses the best tensile properties, with the yield strength of 694 MPa. The enhancement strength is due to the addition of V element with small atomic radius, which is caused by a variety of strengthening mechanisms, including solid solution strengthening and grain refinement strengthening. Most of the reported Al–Nb–Ti–V–Zr system refractory high entropy alloys have poor deformability at room temperature, and most of the work is focused on their compression properties. The Al0.5NbTi3VxZr2 refractory high entropy alloys prepared in the present work not only have excellent compression deformability, but also excellent tensile properties. Our present study not only promotes the development of toughening Al–Nb–Ti–V–Zr system refractory high entropy alloys to challenge engineering applications, but also provides guidance for the design of lightweight high temperature materials with a variety of strengthening mechanisms.