Control of L1₂ Precipitates and Their Impact on Mechanical Properties and the Corrosion Resistance of High-Entropy Alloys

The utilization of CoCrNiAlTi-type high-entropy alloys (HEAs) as high-temperature materials, particularly those reinforced by L1₂ precipitates, demonstrates significant potential. The formation of coherent L1₂ precipitates results from the competition between continuous precipitation (CP) and discontinuous precipitation (DP), which can be controlled by aging temperature, aging time, and grain size. The variations in these precipitates can be quantified through lattice misfit, facilitating the assessment of the stress fields surrounding the precipitates. This quantification is essential for optimizing their mechanical properties and performance.<br/>In this study, HEAs exhibiting varying precipitation behaviors depending on heat treatment time and process were developed. The correlation between their mechanical properties and precipitation behavior was systematically analyzed. Furthermore, the enhancement of mechanical properties due to L1₂ precipitation was compared and analyzed alongside the superior corrosion resistance of these alloys. The study systematically investigates the impact of L1₂ precipitates on corrosion resistance, providing critical insights into developing materials that are not only mechanically robust but also exhibit exceptional resistance to corrosive environments. By quantifying precipitation behavior through lattice misfit and correlating it with mechanical and corrosion properties, this comprehensive analysis offers a clear direction for the development of HEAs optimized for extreme environments. The ability to quantify precipitation behavior using lattice misfit and analyze its correlation with mechanical properties and corrosion resistance is crucial for developing reliable models and simulations. This enables the precise control of microstructural features and guides the design of advanced materials for demanding applications.