The short-range ordering and atomic segregation in various phases of high-entropy alloy during the solidification process

Abstract

High-entropy alloys (HEAs) are highly regarded as promising industrial materials for their unique properties, which are largely determined by their short-range ordering (SRO) and atomic segregation. However, the lack of knowledge on atomic segmentation and SRO during solidification process has hindered the design and synthesis of HEAs. Herein, we conducted molecular dynamics simulations combined with Mont Carlo calculations on FeCoNiCuAl HEA to investigate the SRO and atomic segregation during solidification process. Our findings reveal that the BCC phase exhibit stronger competitiveness during homogeneous crystallization. The SRO and atomic segregation are driven by the enthalpy of mixing for unlike atomic pairs, resulting in an energetically favorable atomic configuration and structure distribution. In the solidified FeCoNiCuAl system, Al-Fe pairs are favored in BCC phase while Co-Ni pairs dominate in the FCC phase. Cu tends to segregate at the edge of the FCC phase without forming intermetallic compounds with other elements. Furthermore, optimized atomic configuration and structure distribution at 700 K and 500 K are not energy-favorable at 300 K, indicating that atomic segregation in the HEA occur throughout the crystallization process. These findings hold significant implications for the design and preparation of HEAs with desirable structures and properties.

Keywords

• Short-range ordering
• Atomic segregation
• Phase formation
• High-entropy alloy
• Molecular dynamics