Equilibrium phase of high-entropy FeCoNiCrCu0.5 alloy at elevated temperature

The phase transformations of FeCoNiCrCu0.5 alloy with the as-cast structure and heat-treated structures were studied. The as-cast alloy specimens were first heated at 1050 degrees C with a holding time of I h. Serial heat-treatment processes at 350 degrees C, 500 degrees C, 650 degrees C, 800 degrees C, 950 degrees C, 1100 degrees C, 1250 degrees C and 1350 degrees C with a holding time of 24 h were then carried out to understand the phase evolution and the relationship between the microstructure and the hardness of the specimens. The microstructures were investigated and chemical analyses performed by optical microscopy (OM), scanning elector microscopy (SEM), X-ray diffractometer (XRD) and transmission elector microscopy (TEM). The results show that FCC peaks were observed from the X-ray diffraction of the as-cast specimens and a precipitate phase was present in the specimens that had been heated to 950 degrees C. The hardness of the FeCoNiCrCu0.5 alloy remained unchanged in the specimens that underwent various heat treatments that were applied in this study. (C) 2009 Elsevier B.V. All rights reserved.