Hierarchical microstructure and enhanced mechanical properties of SLM-fabricated GH5188 Co-superalloy

In this paper, the GH5188 Co-based superalloy was fabricated by selective laser melting (SLM), and its microstructure was systematically investigated. A typical hierarchical microstructure with a < 001 > texture along the building direction is formed during SLM, and each elongated grain consisted of extremely fine (<1 mu m) cells. Meanwhile, the cell boundaries were enriched with W, Cr, and Mn, while Ni was diluted, which formed fine M23C6/M6C eutectic carbides (similar to 80 nm). Nano-indentation tests and tensile tests were applied to test the mechanical properties. The as-SLM samples exhibited excellent performance as well as nano-hardness, strength, and ductility when compared to forging and casting samples. These results suggested promising potential for SLMfabricated GH5188 superalloy parts.