Enabling Multi-Material Structures of Co-Based Superalloy Using Laser Directed Energy Deposition Additive Manufacturing

Abstract

Cobalt superalloys such as Tribaloys are widely used in environments that involve high temperatures, corrosion, and wear degradation. Additive manufacturing (AM) processes have been investigated for fabricating Co-based alloys due to design flexibility and efficient materials usage. AM processes are suitable for reducing the manufacturing steps and subsequently reducing manufacturing costs by incorporating multi-materials. Laser directed energy deposition (laser DED) is a suitable AM process for fabricating Co-based alloys. T800 is one of the commercially available Tribaloys that is strengthened through Laves phases and of interest to diverse engineering fields. However, the high content of the Laves phase makes the alloy prone to brittle fracture. In this study, a Ni-20%Cr alloy was used to improve the fabricability of the T800 alloy via laser DED. Different mixture compositions (20%, 30%, 40% NiCr by weight) were investigated. The multi-material T800 + NiCr alloys were heat treated at two different temperatures. These alloy chemistries were characterized for their microstructural, phase, and mechanical properties in the as-fabricated and heat-treated conditions. SEM and XRD characterization indicated the stabilization of ductile phases and homogenization of the Laves phases after laser DED fabrication and heat treatment. In conclusion, the NiCr addition improved the fabricability and structural integrity of the T800 alloy.

Laser Powder Bed Fusion of Hard‐Phase Containing Co‐Base Alloy

“…Aydogan et al examined the processing of the Co superbase alloy T800. [ 14 ] By alloying with certain amounts of a NiCr‐alloy, the DED processability of the alloy T800 could be improved, and a homogeneous distribution of the Laves phase could be achieved after heat treatment. In addition to the processing of Co‐based superbase alloys or the alloys Stellite 21 and Stellite 6, the utilization of Co‐based alloys with a high hard phase content to achieve higher resistance to abrasion wear is of high technological interest, especially for the AM of tools.…”