BCC+L21 dual-phase Cu40Al20Ti20V20 near-eutectic high-entropy alloy with a combination of strength and plasticity

To pursue a combination of strength and plasticity, a near-eutectic high-entropy alloy Cu40Al20Ti20V20 was developed by using a stoichiometric ratio of the L21 Cu2AlTi ordered phase. The results showed that a softhard alternating BCC (alpha)+L21 (fi) dual-phase structure was realized. The as-cast alloy was composed of BCC (alpha p) dendrites, and a lamellar and rod-like BCC+L21 Cu2AlTi (alpha + fi) eutectic structure with a small amount of FCC Cu-rich phase embedded within. Due to the soft-hard dual-phase structure and large number of phase interfaces of the eutectic, the as-cast alloy possessed a high yield strength of 1300 MPa and plasticity of 6.3%. Annealing facilitated the precipitation of a substantial number of L21 nanoparticles (fiII) in the dendrites and the diffusion of Cu atoms from the Cu-rich phase to the matrix. The desolation transformation of fiII and the Cu diffusion during annealing increased the formation of excess L21 hard-phase to ~50 vol%. Many micro-pores were also formed, which facilitated crack initiation and deteriorated the strength and plasticity of the homogenized alloy.

Automated summary

A near-eutectic high-entropy alloy with a soft-hard dual-phase structure was developed by adjusting the composition ratio and annealing process. The alloy exhibited high yield strength and moderate plasticity, but the homogenization process resulted in the formation of micro-pores, leading to a decrease in mechanical properties.