A new method to design eutectic high-entropy alloys by determining the formation of single-phase solid solution and calculating solidification paths

Abstract

Eutectic high entropy alloys (EHEAs), as an important branch of high entropy alloy field, have attracted wide attention due to their excellent mechanical properties and superior castability. However, it is still an challenge to design the EHEAs. In this paper, we proposed a new method to design EHEAs by determining the formation of single-phase solid solution and calculating solidification paths (using JMatPro software). The eutectic composition can be predicted in the solidification path analysis where two phases (eutectic) solidified simultaneously when no inflexion point appears on the cooling curves of constituent phases. Correspondingly, three EHEAs are successfully designed, like NiAl–Mo8.7Cr8.7V8.7, NiAl–Mo14.5Cr14.5Fe14.5 and NiAl–Mo10Cr10V10Fe10 EHEAs. The microstructures of three EHEAs are investigated by SEM (EDS), TEM and XRD, and are composed of eutectic dendrites with lamellar structure. This type of EHEAs consist of B2 (NiAl) and BCC (like MoCrV, MoCrFe and MoCrVFe) phases with semi-coherent relation, and the nano-sized precipitates form in the two constituent phases, thus possessing the better mechanical properties compared to the great majority of EHEAs. Moreover, we also discuss the deformation mechanism that B2 phase firstly yields and deforms plastically compared to BCC phase.