Mechanical alloying and spark plasma sintering of AlCrCuFeZn high entropy alloy

The AlCrCuFeZn multi-component high entropy alloy was synthesised by mechanical alloying and spark plasma sintering (SPS). Alloying behaviour, microstructure and phase stability were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). In the metastable as-milled condition, two disordered body centred cubic (BCC) phases were observed with crystallite size less than 40 nm. SPS was efficient in obtaining high densification, 91%, in the sintered condition. The structural evolution during the sintering occurred by the formation of two stable phases, one enriched in CuZn with Cu5Zn8-type structure, and another enriched in FeAlCr with a BCC structure. High hardness of 661 and 627 HV was obtained in the as-milled powder and SPS sintered sample, respectively.