Phase Evolution and Mechanical Behaviour of Co–Fe–Mn–Ni–Ti Eutectic High Entropy Alloys

摘要

The current study is aimed to understand the microstructure evolution in Co~(20)Fe~(20)Mn~(20)Ni~(20)Ti~(20)and Co~(25)Fe~(25)Mn~(5)Ni~(25)Ti~(20)high entropy alloys (HEAs). The complete X-ray diffraction and scanning electron microscopy coupled with energy dispersive spectroscopy analyses are carried out to recognize the phases in addition to understand the series of phase development in the presently studied HEAs. For Co–Fe–Mn–Ni–Ti HEAs, at first BCC (β) phase primary dendritic phase is created from the liquid, followed by peritectic reaction to form FCC (α) phase (i.e. BCC (β)?+?L?→?FCC (α)). Then the left over liquid undergoes eutectic reaction to form FCC (α) and Ti~(2)(Ni, Co) phases (i.e. L?→?FCC (α)?+?Ti~(2)(Ni, Co)). Furthermore, the pseudo quasi-peritectic reactions i.e. L?+?BCC (β)?→?FCC (α) +Ti~(2)(Ni, Co) has been proposed based on the microstructure evolution study in case of Co–Fe–Mn–Ni–Ti HEAs. It is important to note that Co–Fe–Mn–Ni–Ti HEAs show eutectics between FCC (α) and Ti~(2)(Ni, Co) phases. The multicomponent Co~(25)Fe~(25)Mn~(5)Ni~(25)Ti~(20)eutectic HEA shows the retention of high strength at elevated temperature.