A combinatorial assessment of microstructure and mechanical properties in AlCrCuFeNi2Vx concentrated alloys

Abstract

This study developed a novel series of AlCrCuFeNi2Vx (x = 0, 0.3 and 0.6) high-entropy alloys (HEAs), and systemically assessed the relationship between composition, processing, microstructure and mechanical properties. The alloys were produced by arc melting and studied in as-solidified and homogenized (annealing at 650 ℃ for 4 h) conditions. In the base alloy of AlCrCuFeNi2, the microstructure consists of disordered bcc and fcc phases, ordered B2 and L12 phases, and the B2 phase and bcc phase are coherent. With the increase of V content, the volume fraction of bcc/B2 phases increase, accompanied with a peculiar phenomenon that the shape of B2 phase has transferred from irregular matrix to spherical precipitates, which caused by the increase of lattice misfit after V addition. Moreover, a large number of Cu particles are randomly distributed in the NiAl (B2) phase, and the crystal structure of Cu particles has changed from 9 R structure to fcc structure after annealing treatment. Mechanical tests of these alloys reveal that the 0.6 at% V addition has doubled the yield strength (V0, 780 MPa; V0.6, 1673 MPa) for the increase in volume fraction of bcc/B2 phase and the solid solution strengthening produces by V addition. The yield strength is increased by 124 MPa after annealing treatment in V0.6 alloy without sacrificing the ductility due to the promotion of L12 phase after annealing treatment.