Microstructure, phase stability and properties of CoCr_0.5Cu_xFe_yMoNi compositionally complex alloys

Abstract

Liquid-phase separation occurred in CoCrCu x FeMoNi (x ≥ 0.5) alloys when the mixing entropies are positive in our previous work. So in this work, CoCr 0.5 Cu x Fe y MoNi alloys are designed to investigate the microstructure, component phases and properties. FCC and BCC were detected in CoCr 0.5 Cu x Fe y MoNi alloys, accompanied with a topologically close-packed μ phase. A parameter, V R , was defined, where V R is the ratio of the volume fraction of BCC plus μ phases and that of FCC phase. The maximum strength and the ductility were obtained at the minimum V R of the alloys, whereas the hardness increased with the increasing V R . It can be presumed that the strange balance between strength, ductility and hardness is an indirect result of the degree of brittle failure.

Compositional Dependence of Phase Selection in CoCrCu0.1FeMoNi-Based High-Entropy Alloys

“…HEAs are defined as alloys containing at least five major elements wherein every major element has an atomic fraction between 5% and 35% [9]. Various studies on HEAs, including composition, processing, crystal structure and microstructure, and physical and mechanical properties, have been performed in the past years [5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23]. …”

The effect of Ti addition on phase selection of CoCrCu0.5FeNi high-entropy alloys

“…Furthermore, HEAs with multi-phases including simple solid solution and intermetallic compounds have been studied [19][20][21][22]. When Ti was added to AlCrFeCoNiCu alloy, equal atomic AlCrFeCoNiCuTi alloy showed a compressive strength of 1356 MPa and a fracture strain of 9% [23].…”