Effects of Iron on Microstructure and Properties of CoCrFe_xNi Multi-principal Element Alloys

In this work, CoCrFe_xNi (x = 2, 3, 4) multi-principal element alloys were designed and synthesized by vacuum arc melting technique, and effects of Fe on microstructure and properties of CoCrFe_xNi alloys were investigated. The crystal phase and microstructure of these alloys were studied by X-ray diffraction and scanning electron microscopy, while mechanical properties were measured by Vickers hardness and compressive tests, respectively. The CoCrFe_xNi alloys presented a single face-centered cubic (FCC) structure with columnar crystal morphology, indicating that the Fe content doesn’t change the microstructure of CoCrFe_xNi alloys. However, the lattice parameters of FCC phases decreased with the addition of Fe element. It was found that all the alloys exhibited excellent ductility without fracture. In addition, the yield strength decreased, and the Vickers hardness varied from 124 HV for CoCrFe₂Ni to 109 HV for CoCrFe₄Ni.