Structure formation and mechanical properties of the high-entropy AlCuNiFeCr alloy prepared by mechanical alloying and spark plasma sintering

Abstract

The phase and structural transformations in equiatomic powder compositions of the Al-Cu-Ni-Fe-Cr system during mechanical alloying (MA), annealing and subsequent spark plasma sintering (SPS) had been studied by X-ray diffraction analysis, scanning and transmission electron microscopy, and differential scanning calorimetry. It has been established that the nanocrystalline high-entropy AlCuNiFeCr alloy synthesized during MA consists of a supersaturated solid solution with a bcc crystalline structure. After annealing and spark plasma sintering at 800 °C, the alloy becomes three-phased, and consists mainly of one B2-ordered solid solution, one fcc solid solution (25 wt %), and of the (Сr, Fe)23C6 phase (8 wt %). The Vickers hardness of the sintered AlCuNiFeCr alloy was 8.35 GPa, and the compressive strength at room temperature reached 1960 MPa.