Synthesis of FeCrCoNiCu high entropy alloy through mechanical alloying and spark plasma sintering processes

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FeCrCoNiCu high entropy alloy (HEA) was produced through mechanical alloying (MA) and spark plasma sintering (SPS) processes. Using X-Ray diffraction, scanning electron microscopy, differential scanning calorimetry, and shear punch testing, the structural, microstructural, and mechanical properties of the milled and SPSed samples were evaluated. After 50 h of milling, a dual-phase solid solution HEA formed consisting of a major FCC phase and a minor BCC phase. Increasing milling time and repeated deformation of the powders led to increased strain and dislocation density, and eventually, an alloy with a uniform distribution of particles with reduced size was achieved. Sintering of the alloy at 750 °C resulted in the annihilation of the BCC phase and the formation of a sigma phase. Moreover, segregation of the elements due to the different mixing enthalpies led to the formation of a new FCC phase. Results revealed that the SPSed alloy that was properly sintered had a porosity of less than 8%, which resulted in good final mechanical properties such as ultimate shear strength of 300 MPa and ultimate tensile strength of 540 MPa.