Laser remelting of a novel carbide-reinforced Ni-Co-Cr-Hf-C alloy with ultra-fine HfC dispersion

• Published in: Materials letters Vol. 366; p. 136495
• Main Authors: Cazic, I., Anvari, P., Aranda, L., Rapin, C., Panteix, P.-J., Berthod, P., Hecht, U.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.07.2024
• Subjects: Additive Manufacturing; Carbides; Ni-based alloy; Particle dispersion; Solidification; Additive Manufacturing; Particle dispersion; Carbides; Ni-based alloy; Solidification
• ISSN: 0167-577X; 1873-4979
• DOI: 10.1016/j.matlet.2024.136495

•A new alloy Ni-Co-Cr-Hf-C was designed for laser powder bed fusion (LPBF).•Laser remelting of a cast substrate was used to mimic LPBF conditions.•An ultra-fine dispersion of stable nano-sized HfC particles was obtained.•The mean particle diameter is 54 nm with an interparticle distance of 325 nm. The dispersion of stable nano-particles is essential for improving the high temperature creep properties of Ni-base alloys. Additive manufacturing by laser powder bed fusion (LPBF) offers novel means to tailor particle distributions taking advantage of the fast and directional solidification inside travelling melt pools. To benefit of this opportunity, a novel in-situ carbide reinforced alloy Ni − 32Co − 28Cr − 3.5Hf − 0.25C (wt. %) was developed. In a first rapid approach laser remelting of a cast alloy block was used to mimic LPBF solidification conditions. After a subsequent annealing treatment at 1150 °C for 6 h, an ultra-fine and intragranular dispersion of nano-sized HfC particles was obtained. The HfC particles have an average size of 54 nm and a mean inter-particle distance of 326 nm, which is an exceptional refinement compared to the as-cast microstructure. The number density of HfC particles ranges around 1 × 1012/m2 in 2D and is estimated to be 2 × 1019/m3 in 3D.