MSE: Seminar: Dr. Gianna Valentino, UMD
Wednesday, September 27, 2023
2118 Chemical and Nuclear Engineering Building
Additively Manufactured Refractory Alloys for High Temperature Environments
Abstract: Advances in additive manufacturing (AM) promise to be a game-changer in the fabrication and implementation of refractory-based components via near-net-shape processing. However, the high melting temperatures of refractories necessitate the redevelopment of AM processing parameters compared to traditional AM metals (e.g., superalloys, steels). In this study, AM laser parameters were developed for tungsten and tantalum alloys and characterized their mechanical behavior to understand the processing-structure-property relationships. Computational fluid dynamics simulations are used to inform a subset of AM laser parameters that are manufactured and characterized for porosity and underlying microstructure. While low porosity is typically a key metric for success in most AM processing, the results presented here will discuss the need to balance maximizing bulk material density while also minimizing cracking from steep thermal gradients. In addition to room temperature mechanical properties, a study to measure the high temperature (up to 2000°C) tensile properties at mm-cm length scales is ongoing and the results will be discussed. Moreover, detailed electron microscopy is also ongoing to elucidate the influence of highly anisotropic AM microstructures on the mechanical response of these AM refractory alloys, including anomalous strain hardening at 400°C and significantly increased plasticity at 1000°C in AM tantalum. Although still in its infancy, a study to fabricate refractory graded materials is currently underway and the results will be discussed for thermal management.