Elmet reports tensile properties of C103 Nb-based refractory alloy following R512E coating and heat treatment
January 20, 2025
A team from Elmet Technologies has published research in the International Journal of Refractory Metals and Hard Materials that looks at the impact of common post-processing techniques on the tensile properties of additively manufactured niobium-based refractory alloy.
In the paper, ‘Tensile properties of R512E coated NbC103 manufactured using laser powder bed fusion,’ the mechanical properties of C103 with an R512E coating were evaluated and compared against common post-processing techniques, including Hot Isostatic Pressing (HIP) and two different heat treatment procedures.
C103 is a niobium-based refractory alloy commonly used in the aerospace industry. To protect the metal from high-temperature oxidising environments, the alloy is often finished with an environmental barrier coating. A common coating for this material is known as R512E, a disilicide slurry applied and cured with heat.
For the research, spherical C103 powder was provided by HC Starck Solutions (now Elmet Technologies) and was manufactured using an electrode induction gas atomisation (EIGA) process. Powder size distribution (PSD) was analysed using a Microtrac S3500, providing results for D10, D50 and D90 as 11, 28 and 47 μm, respectively. Elemental composition of the powder was analysed using the inductively coupled plasma (ICP) technique and interstitial gas analysis (IGA) was performed to measure oxygen content.
The researchers produced tensile specimens in both horizontal and vertical orientations, manufactured using a Renishaw AM400 metal Additive Manufacturing machine. Samples were post-processed via Hot Isostatic Pressing, coated, and further heat treated to simulate a typical operating environment for the coated material. Tensile tests were then conducted at room temperature and compared to ASTM B654 standards for wrought C103.
The researchers highlighted the effects of HIP, HIP + coat, and HIP + coat + vacuum heat treatment. The team concluded that the as-additively manufactured C103 is capable of meeting ASTM standards of wrought material for strength and elongation. The HIPed material showed significant grain growth and a decrease in strength yet continued to exhibit strength higher than the minimum requirement wrought material. The application of R512E again caused grain growth and lower strength, almost equal to wrought C103.
The researchers suggested that vendors of environmental barrier coatings should, therefore, publish the application temperature and required duration, as it has a direct effect on the mechanical properties that the part designer may not be aware of.
The full paper, ‘Tensile properties of R512E coated NbC103 manufactured using laser powder bed fusion (L-PBF),’ is available here.
www.elmettechnologies.com
