Fast mechanical synthesis, structure evolution, and thermal stability of nanostructured CoCrFeNiCu high entropy alloy

A powder of equiatomic CoCrFeNiCu high entropy alloy (HEA) was prepared by short-term (120 min) energy ball milling (HEBM). Our structural and chemical analysis showed that microsized particles fcc with a grain size 8 nm were obtained after 120 min HEBM at 694/1388 rpm. The structural/phase evolution HEA its thermal stability explored high-temperature XRD 600 °C, 800 °C 1000 DSC up to 1500 through the consolidation SPS characterized using XRD, SEM EDX analyses. In-situ HT during 5.5 h annealing involvement transient phases: bcc phase appeared in 1 disappeared higher temperatures; fcc1 (Cu-rich) arising 2 disappearing 3 annealing. for found result formation single-phase fcc2 lean amount Cu. melting points Cu-rich Cu-depleted HEAs as 1118 1288 (Calphad calculations) 1115 1365 (DSC measurements), respectively. under pressure 50 MPa yielded CoCrFeNiCu0.5 turned thermodynamically more favorable than one. Thus, we can suppose thereupon, appears is metastable because excess Cu atoms. During temperature range 800–1000 precipitates from initial alloy, while “mother phase” transforms into stable phase. compositions phases SPS-consolidated (at °C) determined TEM–EDX Optimal combination be recommended facile route fabrication powders bulk materials good structural/elemental homogeneity.