Research progress on heat treatment regulation and mechanical properties of selective laser melted γ″-strengthened nickel-based superalloys

The thermal stability of the complex non-equilibrium solidified microstructure of the selective laser-melted nickel-based superalloy is different from that of the traditional cast and forged counterparts, and the traditional standard heat treatment process cannot obtain stable structures and excellent properties accordingly. Therefore, it is imperative to clarify the inherent relationship between the characteristics of metastable precipitates in non-equilibrium thermal cycles in additive manufacturing and heat treatment processes, to comprehend behaviors such as grain growth, second-phase precipitation, dislocation evolution, etc., during the thermal treatment of metastable structures. The paper focuses on the γ″ strengthening nickel-based high-temperature alloys (such as IN718 alloy), which are widely used in the fields of aviation engines, and gas turbines and summarizing the research progress in microstructure control during heat treatment and mechanical properties after laser selective melting forming. This article aims to explore the methods for regulating the microstructure and improving mechanical properties of high-temperature alloys under rapid solidification, and further expand the application of laser additive manufacturing technology in hot-end structural materials such as aviation engines and gas turbines.