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Ni and Co based MCrAlY (M = Ni and/or Co), dual phase β and γ/γ'; β = NiAl, γ = Ni (Co, Cr), and γ' = Ni3Al) superalloys exhibit several beneficial high-temperature (>1000°C) (2012°F) strength and corrosion resistance properties. Our study investigates the feasibility of fabricating a commercially available NiCoCrAlY alloy (tradename “Amdry 386”) using laser directed energy deposition (laser-DED). A significant challenge for laser fabrication of bulk structures with Amdry 386 (A386) stems from the presence of relatively higher amounts of brittle β phase than ductile γ/γ' phases. While prior studies report laser fabrication of these materials in coating and cladding configurations, bulk structures have not been realized. Fabrication of A386 bulk structures using laser-DED was unsuccessful due to hot cracking and delamination during and after deposition. Laser-DED fabricated A386 alloy exhibited a metastable, rapidly solidified β-rich microstructure typical to laser processes. To alleviate these challenges, this study systematically evaluates the effects of modifying the A386 alloy by adding 10, 20 and 30% by weight of a Ni-20%Cr (NiCr) alloy (mainly γ/γ'). The A386 + NiCr mixtures were processed using laser-DED, and small coupons from each composition were evaluated using SEM, XRD, and microhardness to characterize the as-processed microstructure. Thermodynamic modeling was performed to determine the phase evolution as a function of the alloy composition. Our results show that the alloy chemistry can be successfully modified to improve the structural integrity of laser processed structures.

Haynes 214, a nickel-based superalloy, and its oxide dispersion-strengthened (ODS) versions (addition of 0.3, and 1.5 wt. % yttria (Y2O3)) have been successfully fabricated using selective laser melting (SLM). For each feedstock formulation, optimal processing conditions were identified and high temperature tensile testing coupons were produced. Feedstock preparation and laser scanning strategy have been proven to be critical in the dispersion of nanoparticles in the metal matrix, as well as preventing the formation of extensive crack networks. The impact of Y2O3 addition on the high-temperature tensile properties of Haynes 214 was evaluated and discussed.