Synthesis of CuCrFeNiTiAlx high entropy alloys by means of mechanical alloying and spark plasma sintering

A series of high entropy alloys (HEA) of the type CuCrFeNiTiAlx were prepared in this work, where x ranged from 0, 0.45, 1, 2.5 to 5 mol-%, while the rest of the metals were added in equimolar fractions. The alloys were processed through two steps: The mechanical alloying of the above mentioned powdered metals, followed by spark plasma sintering (SPS). The aluminium content was varied in the alloy for the purpose of determining the effect that this metal has on the formation of metastable phases in the HEA. The X-ray diffraction results revealed the presence of microstructures with FCC and BCC-phases, solid solutions, as well as aluminium intermetallic compounds, after the SPS. The higher content of aluminium in these alloys, the greater their hardness, explained through the formation of these phases. The synthesised alloys developed microstructures with multimodal grain size, which ranged from 1 to 100 mu m.