Phase Stability and Precipitation in L12-Strengthened CoCrNi Medium-Entropy Alloys at Intermediate Temperatures

Understanding phase stability and precipitation at intermediate temperatures is crucial for tailoring microstructures mechanical properties of L12-strengthened multicomponent alloys. In this study, the precipitate type, morphology, distribution (CoCrNi)100−2x(AlTi)x (x = 3, 5, 7 at.%) medium-entropy alloys (MEAs) 600-900 °C were systematically investigated through a combination scanning electron microscopy, energy dispersive x-ray spectroscopy, diffraction, backscatter thermodynamic calculations. Our results reveal that Al Ti additions promote destabilization supersaturated fcc into L12 σ phases, dominating phases MEAs change from + to L21 as concentrations increase. addition, increasing temperature leads morphology lamellar granular microstructures. The effects alloying aging on stability, behavior, discussed kinetic points view.