Investigation of microstructure and mechanical property of a novel SLM Ni-Co-based superalloys with Ta addition

Abstract

The effect of Ta on microstructural evolution and mechanical properties of a novel Ni-Co-based superalloy was investigated by thermodynamic calculations and selective laser melting (SLM). The results show that the addition of Ta promotes the precipitation of γ' phase and carbide, and slightly increases the volume fraction of γ' phase, consistent with thermodynamic calculations. The formation of stacking faults with enrichment of Ta and Ti in the alloys contribute to the preferential nucleation sites of the η phase, causing a transition from the γ' phase to the η phase. The η phases precipitate from the 3%Ta and 4%Ta alloy and prefer lateral growth at the expense of the γ' phase, resulting in large aspect ratio morphology. Moreover, the addition of Ta content of less than 2.0% in this SLM Ni-Co-based superalloys can significantly increase high-temperature yield and tensile strength.