Chemical Composition and Microstructure of INCONEL 718

INCONEL 718 is a precipitation-hardened nickel-based superalloy widely recognized for its excellent mechanical strength, corrosion resistance, and stability at elevated temperatures. Due to these exceptional characteristics, it has become one of the most extensively used superalloys in demanding engineering applications such as aerospace engines, gas turbines, nuclear reactors, and chemical processing equipment. The superior performance of INCONEL 718 is primarily attributed to its unique microstructure and carefully balanced chemical composition, which includes significant amounts of nickel, chromium, iron, niobium, and molybdenum. These alloying elements contribute to the formation of strengthening phases such as gamma double prime and gamma prime, which enhance the alloy’s resistance to deformation and creep under high-temperature operating conditions. This review paper presents a comprehensive overview of the physical properties of INCONEL 718, with particular emphasis on its density, thermal conductivity, specific heat capacity, thermal expansion behavior, and melting characteristics. The relationship between these physical properties and the alloy’s microstructural features is also discussed to provide a deeper understanding of its performance under extreme service environments. Furthermore, the influence of temperature on the thermophysical behavior of the alloy is examined, highlighting its capability to retain structural integrity and dimensional stability in high-temperature applications. In addition, the review summarizes the key mechanical and thermal characteristics that make INCONEL 718 a preferred material in high-performance engineering systems. By compiling and analyzing findings from previously published research, this study aims to provide a consolidated reference for researchers and engineers interested in the thermophysical behavior and industrial significance of INCONEL 718 superalloy.