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Pegues, Jonathan

Publications and source records attributed to Pegues, Jonathan.

At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Characterization of Refractory Alloys Produced by Laser Additive Manufacturing

Refractory alloys often possess superior thermomechanical properties compared to conventional materials, such as steels, Ni-based superalloys, and Ti alloys, especially in high-temperature environments. While these materials promise to revolutionize numerous industries, significant hurdles remain for insertion into applications due to an incomplete understanding of structure-property relationships and conventional processing challenges. We explore laser-based additive manufacturing (AM) to construct refractory alloys consisting of combinations of Mo, Nb, Ta, and Ti with systematically increasing compositional complexity. Microstructure, composition, and hardness of the AM-processed alloys were characterized. Results are discussed in the context of pairing additive manufacturing with refractory metals to enable next-generation alloys.

Kustas, Andrew B.↗
DOE OSTI2022

Extreme hardness at high temperature with a lightweight additively manufactured multi-principal element superalloy

Materials are needed that can tolerate increasingly harsh environments, especially ones that retain high strength at extreme temperatures. Higher melting temperature alloys, like those consisting primarily of refractory elements, can greatly increase the efficiency of turbomachinery used in grid electricity production worldwide. Existing alloys, including Ni- and Co-based superalloys, used in components like turbine blades, bearings, and seals, remain a performance limiting factor due to their propensity, despite extensive optimization efforts, for softening and diffusion-driven elongation at temperatures often well above half their melting point. To address this critical materials challenge, we present results from integrating additive manufacturing and alloy design to guide significant improvements in performance via traditionally difficult-to-manufacture refractory alloys. We present an example of a multi-principal element alloy (MPEA), consisting of five refractory elements and aluminum, that exhibited high hardness and specific strength surpassing other known alloys, including superalloys. The alloy shows negligible softening up to 800°C and consists of four compositionally distinct phases, in distinction to previous work on MPEAs. Density functional theory calculations reveal a thermodynamic explanation for the observed temperature-independent hardness and favorability for the formation of this multiplicity of phases.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Rapid Quality Assessment in Additive Manufacturing: New Procedure Accelerates Build Quality Assessment. White paper

Accelerated growth of the additive manufacturing (AM) industry in recent years is accompanied by a rising need for methods to quickly assess quality at-scale. Current practices for quality inspection include nondestructive test methods and destructive testing of witness coupons, which are artifacts built alongside the actual part. However, these methods can be costly and time-consuming. Recognizing this need, the Additive Manufacturing Center of Excellence (AM CoE) initiated a project led by its partner, Auburn University, to develop rapid testing procedure using asbuilt samples tested in torsion to quantitatively assess build quality. The presented work developed a rapid testing procedure using as-built samples tested in torsion to quantify small variances for assessing build quality.

42 ENGINEERING↗