Microstructure and properties of periodic porous Inconel 718 alloy prepared by selective laser melting

Periodic porous Inconel 718 (IN718) alloy with a porosity of 54% was prepared by selective laser melting (SLM), and the effects of heat treatment on the microstructure and mechanical properties of the alloy were studied. The austenites with cellular and columnar crystal morphology were formed in IN718 alloy. After standard heat treatment, the Laves phases were decomposed, and more gamma '', gamma' phases and delta phases were precipitated. gamma '' phases were distributed on the boundary and inside of the grain, and 6 phases were mainly distributed on the grain boundary. The average microhardness of IN718 alloy perpendicular and parallel to the building direction increased to 550.49 HV and 362.58 HV, with 143% and 52% increase, respectively. The yield strength and elastic modulus increased to 248.71 MPa and 6.36 GPa, which were notable increases of 46% and 27%, respectively. The uniformly distributed gamma '' and gamma' phases effectively pinned the dislocations and grain boundaries were responsible for the enhanced mechanical properties of the alloys.

Automated summary

By studying the effects of heat treatment on the microstructure and mechanical properties of IN718 alloy, it was found that the hardness, yield strength, and elastic modulus of the alloy significantly increased after heat treatment, mainly due to the effects of gamma'' and gamma' phases.