Laves phase control of inconel 718 superalloy fabricated by laser direct energy deposition via ı aging and solution treatment

In order to achieve the microstructure homogeneity at a lower temperature and improve the mechanical properties, a novel post heat treatment was introduced to Inconel 718 fabricated by laser direct energy deposition (LDED), by means of ı aging treatment + solution treatment. The microstructure analysis shows that the fully precipitation of ı phase in LDED Inconel 718 superalloy can “cut” the long strip Laves phase into small pieces. According with the ı phase solution treated at 1020 ◦C for 30 min, only tiny particle Laves phase was remained. The equilibrium volume fraction of Laves phase after ı phase solution treatment is about 1%, which is much lower than that of the as-deposited sample or the sample only solution treated at 1020 ◦C. Due to the solution strengthening and precipitation of γ'' phase during aging treatment, the tensile strength of ı aging + ı solution + double aging treated samples was 10.27% higher than that of directed solution + double aging treated samples, as well as a 31.38% and 52.71% increases in elongation and the reduction of area during tensile tests.