Research on optimizing strength and ductility of HfNbTaZr dual-phase high-entropy alloy by tuning chemical short-range order

Chemical short-range order (CSRO) plays an important role in the mechanical properties of high-entropy alloys (HEAs). However, the research on the effect of CSRO on the mechanical properties of HEAs only focuses on the single-phase systems, which limits the control of mechanical properties for more HEAs by adjusting CSRO. In this work, the different effects of CSRO on the strength and ductility of single-phase and dual-phase HfNbTaZr are studied by the atomic-scale simulations. The results show that there are differences in the CSRO between single-phase and dual-phase systems. The strength of the single-phase system and dual-phase system both decrease by increasing the CSRO, which was caused by the more severe lattice distortion and higher enrichment degree in the Hf-Zr-rich region. A small amount of HCP (Hexagonal Close Packed) structure plays a role in dispersion strengthening, so the dual-phase system with low CSRO has high strength. The distribution of the Hf-Zr-rich region and the proportion of HCP structure are important factors affecting the ductility. The system, with evenly distributed Hf-Zr-rich regions and a small amount of HCP structure, has better strength and ductility.