Microstructure and high temperature properties of tungsten processed via electron beam melting additive manufacturing. (June 2023)

• Record Type: Journal Article
• Authors: Ledford, Christopher; Fernandez-Zelaia, Patxi; Graening, Tim; Campbell, Quinn; Rojas, Julio Ortega; Rossy, Andrés Márquez; Kato, Yutai; Kirka, Michael M.
• Is Part Of: International journal of refractory metals & hard materials. Volume 113(2023)
• Publication Date: 2023-06
• Subjects: Tungsten -- Crystallographic texture -- Electron beam melting -- Additive manufacturing -- Mechanical properties; Heat resistant alloys -- Periodicals; Refractory materials -- Periodicals; Metallography -- Periodicals; Alliages réfractaires -- Périodiques; Matériaux réfractaires -- Périodiques; Métallographie -- Périodiques; Heat resistant alloys; Metallography; Refractory materials; Periodicals; Electronic journals; 669.73
• DOI: 10.1016/j.ijrmhm.2023.106148
• Languages: English
• ISSNs: 0263-4368

Abstract

Highlights: Fabrication of highly dense crack free pure tungsten via electron beam additive manufacturing. "Texture switch" observed along the build direction microstructure. High temperature tensile properties show material behavior similar to recrystallized tungsten. High dislocation densities were observed in the as-fabricated samples. Highly anisotropic behavior due to the underlying crystallographic anisotropy. Abstract: There is considerable interest in the adoption of additive manufacturing for processing refractory metals. The layer-wise fabrication approach enables opportunities for producing complex geometries which cannot be otherwise be achieved via powder metallurgy. However, the processing science is still in its nascent stages and structure–property relations are relatively unexplored. Fundamental research is needed to further develop the technology and enable the fabrication of refractory metals for high temperature applications. Here we focus on the processing of pure tungsten using electron beam melting additive manufacturing. Experimentally we develop a suitable processing window for achieving high density crack free material. Microstructural analysis reveals that the microstructure generally consists of a columnar structure with a 111 build direction fiber preference, although, fiber switching was observed. Process induced deformation is believed to drive the formation of subgrains whose boundaries exhibit a high dislocation density. High temperature tensile testing reveals that the material exhibits excellent properties closer to that of annealed tungsten. Significant mechanical anisotropy was observed to be present which is likely driven by strong crystallographic texture.