# Structural Particularities, Prediction, and Synthesis Methods in High-Entropy Alloys  
[PERSON]  
1 National R&D Institute for Non-Ferrouns and Rare Metals, 102 Brivintei Blvd, 077145 Pantelimon, Romania, [EMAIL_ADDRESS] (S.C.); [EMAIL_ADDRESS] (L.-R.D.); [PERSON]DRESS] (L.-F.M.); [EMAIL_ADDRESS] (N.V.); [EMAIL_ADDRESS] (L.-M.C.); [EMAIL_ADDRESS] (A.P.)  
[PERSON]  
1 National R&D Institute for Non-Ferrouns and Rare Metals, 102 Brivintei Blvd, 077145 Pantelimon, Romania, [EMAIL_ADDRESS] (S.C.); [EMAIL_ADDRESS] (L.-M.C.); [PERSON]DRESS] (L.-F.M.); [PERSON]_ADDRESS] (N.V.); [PERSON]DDRESS] (N.-M.C.); [EMAIL_ADDRESS] (A.P.)  
[PERSON]  
1 National R&D Institute for Non-Ferrouns and Rare Metals, 102 Brivintei Blvd, 077145 Pantelimon, Romania, [EMAIL_ADDRESS] (S.C.); [EMAIL_ADDRESS] (L.-M.C.); [EMAIL_ADDRESS] (L.-F.M.); [EMAIL_ADDRESS] (N.V.); [EMAIL_ADDRESS] (L.-M.C.); [EMAIL_ADDRESS] (A.P.)  
[PERSON]  
1 National R&D Institute for Non-Ferrouns and Rare Metals, 102 Brivintei Blvd, 077145 Pantelimon, Romania, [EMAIL_ADDRESS] (S.C.); [EMAIL_ADDRESS] (L.-M.C.); [EMAIL_ADDRESS] (N.V.); [EMAIL_ADDRESS] (N.-M.C.); [EMAIL_ADDRESS] (A.P.)  
2  
Footnote 16: email: {[EMAIL_ADDRESS]}  
The development and optimization of HEAs require a deep understanding of their structural characteristics, phase stability, and the underlying mechanisms governing their unique properties. Various theoretical and computational models, such as the CALPHAD (CALculation of PHAse Diagrams) method, have been employed to predict phase stability and guide the design of new HEAs. These models consider the thermodynamic and kinetic aspects of HEAs, including Gibbs free energy calculations, mixing enthalpy, and entropy contributions [4]. The prediction of phase stability in HEAs is a complex task, given the vast compositional space and the interplay of multiple elements. However, advancements in computational techniques and high-throughput experiments have significantly enhanced our ability to design and develop new HEAs with tailored properties.  
Synthesis methods play a crucial role in determining the microstructure and properties of HEAs. Techniques such as arc melting, mechanical alloying, and powder metallurgy are commonly used to produce HEAs. Each synthesis method has its own advantages and limitations, impacting the homogeneity, phase distribution, and overall performance of the resulting alloys. Post-synthesis treatments, such as heat treatment and thermomechanical processing, further influence the microstructure and mechanical properties of HEAs [5]. Advanced characterization techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), are essential for analyzing the phase composition, microstructural features, and defect structures in HEAs [6].  
The exploration of HEAs is still in its early stages, with many challenges and opportunities lying ahead. Future research efforts are expected to focus on optimizing alloy compositions, understanding the fundamental mechanisms driving their properties, and exploring new applications for these versatile materials. The potential of HEAs to revolutionize materials science and engineering is immense, offering new pathways for developing next-generation materials with unprecedented performance and functionality [7].  
In this review, we will delve into the structural particularities of HEAs, exploring their unique microstructural features and stability mechanisms. We will examine the various prediction and estimation concepts used to design and understand HEAs, highlighting the role of thermodynamic and kinetic models. Furthermore, we will discuss the synthesis methods employed to produce HEAs, emphasizing the impact of different techniques on their properties.