Using combinatorial strategies to develop optimized amorphous metals for direct write extrusion based additive manufacturing
Abstract
Using combinatorial strategies to develop optimized amorphous metals for direct write extrusion based additive manufacturingAdditi"ve manufacturing (AM) can create intricate, weight-optimized structures without the need for specific tooling or significant materia""l waste. Whereas AM of (thermo)plastics is highly advanced and broadly commercialized, metal AM techniques are more limited in versa""tility andflexibility. Specifically, prominent metal AM techniques based on scanning of laser and electron beams, are difficult and"" costly to implement, and evolve complex residual stresses that limit size, dimensional accuracy, and complexity of parts. We have r""ecently shown that, due to their unique thermoplastic processability, a subset of amorphous metals, so called bulk metallic glasses"" (BMGs), can be 3D printed with similar ease and versatility than commercially established fusedfilament fabrication of extruded th""ermoplastics.Here, we propose an alloy development strategy where we specifically design BMGs for AM Navy usage. Requirements are f""acile and versatile AM ability, corrosion resistance, paired with mechanical properties required for structural applications. Specif""ically, to realize facile AM ability, a low viscous state of the BMGs~ supercooled liquid state must be present for ease of extrusio"n ability. Such flow behavior must be present over times scales that permit practicalprinting conditions and printing speeds of tens of cubic centimeters per hour for extrusion nozzles of 0.25 millimeter. In addition to such flow requirements the BMGs should possess high oxidation resistance at the printing temperatures to ensure joining in air with the already printed layer to result in high" mechanical properties. For Navy applications, high resistance to corrosion in sea water will be developed by corrosion and electroc""hemical characterizations. In addition to the high strength, that is ubiquitous for BMGs we will develop alloys that also have high" fracture toughnesswhich we will characterize through our recently developed artificial microstructure method. Our overall alloy d"evelopment strategy involves theory, combinatorial synthesis strategiescombined with high-throughput methods, fast characterization"" methods, and state of the artcharacterization methods. Theory, based on packing efficiency of the glass and relative phase stabili""ty, reduces compositional space from the vast composition space spanned by combinations of approximately 32 practical elements, to a" compositional space regions that can be realized in compositional libraries. Such composition libraries are realized in thin film s"ynthesized through combinatorial magnetron sputtering. The thin film libraries, which for glasses have been shown torepresent the b""ulk properties, are characterized through high-throughput methods to evaluate their relative formability ability and corrosion rate."" Within this project we propose to synthesize and characterize ~30,000 alloys. Subsequently, ~100 - 1000 selective alloys that exhib""it highest properties, will be fast characterized through extrusion methods, artificial microstructure approach to determine fractur""e toughness, and electrochemical characterization to determine corrosionbehavior. Best alloys identified through these rapid techni""ques will be fabricated in bulk form andthoroughly characterized for required properties through state-of-the-art methods. Finally," the most promising alloys will be 3D printed and its properties characterized and compared to bulk material. Besides the specific" alloys and technology that we propose to develop within this research, a significant outcome are the unprecedented data of BMG form""ing alloys, and their corrosion behavior. Such data which will be cured, managed, and visualized, will benefit future ONR orgeneral"ly DoD research activities as they lay a foundation for a more directed materials discoveryprocess.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jun 09, 2017
- Source ID
- N000141712568
Entities
People
- Jan Schroers
Organizations
- Office of Naval Research
- United States Navy
- Yale University