Effect of ti on the microstructure and properties of CoCrCuFeNiTix high-entropy alloys

The changes in microstructure and properties as a result of Ti addition to the CoCrCuFeNi equiatomic alloy system were studied. At low Ti additions, i.e. CoCrCuFeNi and CoCrCuFeNiTi0.5, the alloys are composed of an FCC solid solution. However, the CoCrCuFeNiTi0.8 and CoCrCuFeNiTi alloys are composed of an FCC solid solution, a eutectic mixture of FCC and Laves phases (Fe2Ti type), and a fraction of amorphous phase. The compressive yield strength of the alloys increases from 230 MPa to 1272 MPa in the range of Ti addition considered. The CoCrCuFeNiTi0.5 alloy exhibits an especially high compressive strength of about 1650 MPa. Additionly, this alloy exhibits extensive work hardening and a large ductility of 22%. An interesting transition from paramagnetism to superparamagnetism was found. This may be attributed to the appearance of nanoparticles embedded within the amorphous phase as a result of Ti content.