Fabrication and properties of nanocrystalline Co0.5FeNiCrTi0.5 high entropy alloy by MA–SPS technique

Most of multi-component high entropy alloys were designed as equi-atomic or near equi-atomic and were mainly prepared by vacuum arc melting. The present paper reports synthesis of inequi-atomic Co0.5FeNiCrTi0.5 high entropy alloy by mechanical alloying and spark plasma sintering (MA–SPS). Alloying behavior, microstructure and properties of Co0.5FeNiCrTi0.5 alloy are investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and instron testing system, respectively. Both BCC and FCC crystal structure phases are observed after MA, while a FCC phase and additional sigma phase are noticed after SPS. Moreover, numerous nanostructured phases are founded in the alloy after consolidated by SPS. The alloy with a density of 99.15% after SPS exhibits excellent comprehensive mechanical properties. The yield stress, compressive strength, compression ratio and Vickers hardness of the alloy are 2.65 GPa, 2.69 GPa, 10.0% and 846 HV, respectively. The fracture mechanism of this alloy is observed as cleavage fracture and intergranular fracture.

► Nanocrystalline Co0.5FeNiCrTi0.5 high entropy alloy is prepared via MA–SPS.
► Nanocrystalline Co0.5FeNiCrTi0.5 high entropy alloy exhibits excellent comprehensive mechanical properties.
► Polygonal bulk phase, strip shaped crisscrossed phase and nano-sized spherical phase are obtained.
► The fracture mechanism of Co0.5FeNiCrTi0.5 high entropy alloy synthesized by MA–SPS is observed.