The microstructure and properties evolutions of porous Inconel718 alloy by selective laser melting

Abstract

Abstract Nickel-based porous materials possess excellent mechanical properties and can be utilized in the fabrication of diverse lightweight structural materials, holding great potential for applications in the aerospace and automotive sectors. This study focuses on the preparation of porous Inconel718 alloy through selective laser melting and investigates the influence of heat treatment (standard heat treatment, homogenization heat treatment, and homogenization + standardization heat treatment) on the microstructure and properties of the alloy. Inconel718 is a precipitation-strengthened, high-temperature nickel-based alloy. The results indicate that the compressive properties of the porous structures were significantly improved through homogenization heat treatment (the compressive property and energy absorption capacity were increased by 21.8% and 40.4%, respectively). This enhancement can be attributed to the dissolution of a considerable amount of δ phases (Ni3Nb) and Laves phase ((Ni,Cr,Fe)2(Nb,Mo,Ti)) as the solution temperature increased, thereby releasing the strengthening phase -forming element Nb, These Nb elements diffuse uniformly at a high solution temperature, and a large number of nano-sized γ" phases (Ni3Nb) are precipitated in the alloy grains, playing a role of dispersion strengthening and making the strength increase significantly. Moreover, after homogenization heat treatment, the dislocation density is decreased, the crack sensitivity is decreased, and the toughness of the alloy is increased. Consequently, homogenization heat treatment facilitates the dispersion, which thus strengthens the alloy and enhances its compression performance. This study holds significant theoretical and practical implications as it contributes to the advancement of fundamental research on porous high-temperature nickel-based alloys and broadens their range of applications.