@article {2196,
	title = {Navigating the BCC-B2 refractory alloy space: Stability and thermal processing with Ru-B2 precipitates},
	journal = {Acta Materialia},
	volume = {265},
	year = {2024},
	pages = {119628},
	abstract = {<p>
	Refractory multi-principal element alloys (RMPEAs) could provide next-generation high temperature alloys, but their ductility and high temperature strength need significant improvement. Emulating superalloy \&gamma;-\&gamma;\&rsquo; microstructures, RMPEAs combining a ductile BCC matrix with embedded B2 precipitates for strengthening could meet this goal. Two-phase BCC-B2 RMPEAs have recently been demonstrated, but the B2 phase typically exhibits insufficient thermodynamic stability for operating temperatures \&ge;1300 \&deg;C. Using high-throughput CALPHAD predictions, we screen across 3,500 potential BCC-B2 systems. Promising compositions are predicted for alloys combining Ru-based B2s with refractory BCC elements. A total of 20 such compositions were arc-melted to characterize their as-cast and heat-treated microstructures. In these alloys, the RuHf B2 exhibits exceptional stability beyond 1900 \&deg;C but cannot be solutionized. By contrast, RuTi does solutionize and reprecipitate between 1300 and 1900 \&deg;C, providing a robust thermal processing pathway. RuAl can be solutionized but also tends to form competing intermetallic phases. Altogether, Ru-B2 RMPEAs offer great design flexibility and surpass the stability and thermal processability of previously studied BCC-B2 refractory alloys.
</p>
},
	keywords = {B2 phase, Calphad, Combinatorial, High temperature materials, Precipitation strengthening, Refractory multi principal element alloys, Thermal processing},
	issn = {1359-6454},
	doi = {https://doi.org/10.1016/j.actamat.2023.119628},
	url = {https://www.sciencedirect.com/science/article/pii/S1359645423009564},
	author = {Sebastian A. Kube and Carolina Frey and Chiyo McMullin and Ben Neuman and Kaitlyn M. Mullin and Tresa M. Pollock}
}
@article {2211,
	title = {Rapid Screening of Single Phase Refractory Alloys Under Laser Melting Conditions},
	journal = {Materials \& Design},
	year = {2024},
	pages = {112726},
	abstract = {<p>
	Refractory alloys can be difficult to fabricate by laser-based manufacturing methods due to their high melting temperatures, high interstitial solubility, and propensity for low temperature brittleness. Laser-based processes, such as welding and additive manufacturing (AM), yield similar populations of defects, including microsegregation and solidification and solid-state cracking. Given the extreme challenges and cost associated with the production of refractory powders, this research aimed to develop a rapid screening methodology that combines predictive defect formation metrics with single track melting experiments. A flexible single laser track melting platform was designed to perform screening experiments on conventional and multi-principal element refractory alloys across a wide range of laser energy inputs. The platform was employed to investigate laser melting on solid substrates, or on a substrate with a single layer of powder feedstock, and is demonstrated with the highly fabricable Nb-base alloy C103. Preliminary investigations are performed on refractory multi-principal element alloys in the Hf-Mo-Nb-Ta-Ti family, and significant differences in cracking resistance and solidification morphology are observed. Implications for future alloy design and processing strategies for defect-resistant refractory alloys for AM are discussed.
</p>
},
	keywords = {Additive manufacturing, high entropy alloy, multi-principal element alloy, refractory alloys, solid-state cracking, solidification cracking},
	issn = {0264-1275},
	doi = {https://doi.org/10.1016/j.matdes.2024.112726},
	url = {https://www.sciencedirect.com/science/article/pii/S0264127524000984},
	author = {Kaitlyn M. Mullin and Carolina Frey and James Lamb and Sophia K. Wu and McLean P. Echlin and Tresa M. Pollock}
}
