Microstructure and mechanical performance of ODS superalloys manufactured by selective laser melting

Selective Laser Melting (SLM) is a uniquely advantageous method to prepare Oxide Dispersion Strengthened (ODS) superalloys. In this paper, IN718 powder and 1 wt% Y2O3 powder were mixed by ball milling as raw materials, and the samples were prepared by SLM at different laser scanning speeds in order to investigate the densification, microstructure and mechanical properties of SLM-ODS superalloys under different laser energy densities. The results showed that when the laser energy density was 356 J/m, the density of the alloy could reach 99.66%. With the increase of laser energy density, the microstructure of alloy was transformed from cellular dendrites to columnar dendrites, and the hardness and strength of the materials were improved in varying degrees. Y2O3 was uniformly dispersed in the matrix, and the hardness and strength of the alloy were improved compared with SLM-IN718 due to its dispersion strengthening and fine grain strengthening. When the energy density was 300 J/m, the yield strength and tensile strength of the material reached the highest, 850.14 MPa and 1099.58 MPa respectively, due to the precipitation of metal carbides. At 650 degrees C, the tensile strength of the alloy was 100 MPa higher than that of SLM-IN718 due to the strength sag resistance effect of the dispersed oxide.