Paul Gradl

Mr. Paul Gradl

National Aeronautics and Space Administration, Washington, District of Columbia, USA
orcid

Research Focus & Metrics

Academic Career Length

18Years (2009-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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19 April 2023 in Nature
Verified
Journal Article
Open access
PDF file
TSTimothy M. Smith
Timothy M. Smith
CKChristopher A. Kantzos
Christopher A. Kantzos
NZNikolai A. Zarkevich
Nikolai A. Zarkevich
BHBryan J. Harder
Bryan J. Harder
MHMilan Heczko
Milan Heczko
JLJohn W. Lawson
John W. Lawson
Multiprincipal-element alloys are an enabling class of materials owing to their impressive mechanical and oxidation-resistant properties, especially in extreme environments1,2. Here we develop a new oxide-dispersion-strengthened NiCoCr-based alloy using a model-driven alloy design approach and laser-based additive manufacturing. This oxide-dispersion-strengthened alloy, called GRX-810, uses laser powder bed fusion to disperse nanoscale Y2O3 particles throughout the microstructure without the use of resource-intensive processing steps such as mechanical or in situ alloying3,4. We show the successful incorporation and dispersion of nanoscale oxides throughout the GRX-810 build volume via high-resolution characterization of its microstructure. The mechanical results of GRX-810 show a twofold improvement in strength, over 1,000-fold better creep performance and twofold improvement in oxidation resistance compared with the traditional polycrystalline wrought Ni-based alloys used extensively in additive manufacturing at 1,093 °C5,6. The success of this alloy highlights how model-driven alloy designs can provide superior compositions using far fewer resources compared with the ‘trial-and-error’ methods of the past. These results showcase how future alloy development that leverages dispersion strengthening combined with additive manufacturing processing can accelerate the discovery of revolutionary materials.

18 April 2022 in Journal of Materials Engineering and Performance
Verified
Journal Article
Open access
PDF file
Paul GradlPaul Gradl
Paul Gradl
DTDarren C. Tinker
Darren C. Tinker
APAlison Park
Alison Park
OMOmar R. Mireles
Omar R. Mireles
MGMarissa Garcia
Marissa Garcia
CMChristopher Mckinney
Christopher Mckinney
Metal additive manufacturing (AM) encapsulates the myriad of manufacturing processes available to meet industrial needs. Determining which of these AM processes is best for a specific aerospace application can be overwhelming. Based on the application, each of these AM processes has advantages and challenges. The most common metal AM methods in use include Powder Bed Fusion, Directed Energy Deposition, and various solid-state processes. Within each of these processes, there are different energy sources and feedstock requirements. Component requirements heavily affect the process determination, despite existing literature on these AM processes (often inclusive of input parameters and material properties). This article provides an overview of the considerations taken for metal AM process selection for aerospace components based on various attributes. These attributes include geometric considerations, metallurgical characteristics and properties, cost basis, post-processing, and industrialization supply chain maturity. To provide information for trade studies and selection, data on these attributes were compiled through literature reviews, internal NASA studies, as well as academic and industry partner studies and data. These studies include multiple AM components and sample build experiments to evaluate (1) material and geometric variations and constraints within the processes, (2) alloy characterization and mechanical testing, (3) pathfinder component development and hot-fire evaluations, and (4) qualification approaches. This article summarizes these results and is meant to introduce various considerations when designing a metal AM component.

1 May 2021 in Acta Astronautica
Verified
Journal Article
Closed access
FKFabio Kerstens
Fabio Kerstens
Angelo CervoneAngelo Cervone
Angelo Cervone
Paul GradlPaul Gradl
Paul Gradl

1 September 2020 in Acta Astronautica
Verified
Journal Article
Closed access
Paul GradlPaul Gradl
Paul Gradl
CPChristopher S. Protz
Christopher S. Protz

29 June 2023 in Acta Astronautica
Verified
Journal Article
Open access
Paul GradlPaul Gradl
Paul Gradl
OMOmar R. Mireles
Omar R. Mireles
CKColton Katsarelis
Colton Katsarelis
TSTimothy M. Smith
Timothy M. Smith
JSJeff Sowards
Jeff Sowards
CKChristopher Kantzos
Christopher Kantzos

1 July 2021 in Materials Science and Engineering: A
Verified
Journal Article
Open access
GDGabriel Demeneghi
Gabriel Demeneghi
BBBaxter Barnes
Baxter Barnes
Paul GradlPaul Gradl
Paul Gradl
JMJason R. Mayeur
Jason R. Mayeur
KHKavan Hazeli
Kavan Hazeli