Evolution of microstructure and mechanical characteristics of (CrFeNiCu)_100-xTi_x high-entropy alloys

(CrFeNiCu)(100-x)Ti-x (x = 0, 3, 5, 7 and 10; at%) high-entropy alloys have been designed by the consideration of the thermophysical relationship between Ti and other principal elements to investigate the influence of Ti on the microstructural evolution and mechanical properties of (CrFeNiCu)(100-x)Ti-x high-entropy alloys. The addition of Ti content in HEAs leads to a change in phase formation from dual-phase (FCC1 and FCC2, FCC: face-centered cubic) to the mixture of FCC1, FCC2 phases, and an additional body-centered cubic (BCC) phase. The yield strength and Vickers hardness of the alloys are enhanced from 291 to 1511 MPa and HV 134 to HV 531, respectively, which depends strongly on the volume fraction of BCC phase. On the one hand, the plasticity of the alloys reduces from 45.00% to 24.09%, but it could be considered reasonable plasticity. These results revealed that the addition of a minor alloying element in high-entropy alloys with consideration of thermophysical parameters led to the formation of a multiple solid solution structure with excellent mechanical properties.