CoCrFeMnNi high-entropy alloys reinforced with Laves phase by adding Nb and Ti elements

Laves phase plays a positive role in improving the strength of high- entropy alloys (HEAs); Nb and Ti elements have potential to promote Laves phase formation in some HEAs. For improving the strength of the face- centered cubic (FCC) CoCrFeMnNi HEA, a series of (CoCrFeMnNi)(100-x)Nb-x (atomic ratio: x 5 0, 4, 8, 12, 16) and (CoCrFeMnNi)(100-x)Ti-x (atomic ratio: x 5 0, 2, 4, 6, 8, 12) HEAs were prepared by melting. The effects of Nb and Ti on the microstructure evolution and compressive properties of the CoCrFeMnNi HEAs were investigated. For (CoCrFeMnNi)(100-x)Nb-x HEAs, the second- phase (Laves and r phase) volume fraction increased from 0 to 42%. The yield strength also increased gradually from 202 to 1010 MPa. However, the fracture strain decreased from 60% (no fracture) to 12% with increasing Nb content. For (CoCrFeMnNi)(100-x)Ti-x HEAs, the yield strength increased from 202 to 1322 MPa. The Laves phase volume fraction also increased from 0 to 27%. However, the fracture strain decreased from 60% (no fracture) to 7.5% with increasing Ti content. Addition of Nb and Ti has a good effect on improving the strength of FCC CoCrFeMnNi HEA.