Top-down Design and Processing of Light Weight Alloys

National Laboratory: 
Lawrence Livermore National Laboratory
Oak Ridge National Laboratory
Characterization Class: 
Mechanical Behavior of Materials
Microscopy
Computational Tools Class: 
Materials Processing
Structure-Properties
Processing/Manufacturing Class: 
Fabrication and synthesis
Description: 

Large volume manufacturing of complex geometry components such as cylinder heads, engine block and turbo charger compressor impellers require castable ligh weight alloys that retain mechanical properties at elevated temperatures. Although promising, the manufacturing of complex components that contain of a large fration of intermetallic via traditional powder metallurgy and advanced casting methods is challenging and cost prohibitive in many applications. This effort will circumvent many of these limitations by focusing on the development of alloys that can be directly cast into near net shape components and require little or no heat-treatment.ORNL and LLNL are an established team in developing intermetallic strengthened aluminum alloys. The team focuses on top-down design and processing of alloys. Typically, lightweight alloys use bottom-up approaches, where clusters of solute atoms are allowed to diffuse and disrupt the matrix phase via the formation of clusters, effectively strengthening the material. In contrast, top-down alloy design exploits sharp changes in solubility to form strengthening architectures during solidification. Top-down alloy design has the potential to minimize heat treatments and enhance thermal stability and high-temperature physical properties to design advanced materials with optimum performance. Computational alloy theory combines well-established approaches: density function theory for predicting alloy energetics (when needed) and Computer Coupling of Phase Diagrams and Thermochemistry, or CALPHAD, to assess the thermodynamic properties of complex multi-component alloys. Along with CALPHAD, tools have been designed to search for alloy compositions that lead to appropriate properties in terms of melting temperature; fraction of ductile and precipitate phases; and other properties, such as viscosity, thermal conductivity, or magnetism. This approach already has been applied successfully to actinide alloys for advanced nuclear fuels, bulk amorphous alloys, and rare-earth-based alloys. This theory component greatly benefits from experimental data on phase characterization, formation heat, and magnetism as a function of alloy composition, temperature, and (possibly) pressure to support the search for solutes without compromising on target properties for applications. This has been demonstrated for rare-earth-based alloys. Reflecting the recent Materials Genome Initiative's goals, our cost-efficient informatics-based quantitative framework effectively integrates Edisonian and rational methods for efficient and accelerated materials design and processing that can be applied broadly in all areas of materials development and, on occasion, to reverse-engineer materials with target properties.

Capability Bounds: 

Capability limitations are subject to desired measurements.

Unique Aspects: 

To develop new materials, the team has expertise using density functional theory, CALPHAD, electromagnetic processing, and thermomechanical processing. Capabilities include: thermodynamic modeling, transmission electron/scanning electron microscopies, neutron and x-ray scattering, and high magnetic field and electromagnetic processing.

Availability: 

Capabilities are available through cooperative research and development agreements (CRADAs), sponsored research, Manufacturing Demonstration Facility technical collaboration, and the Critical Materials Institute.

Single Point of Contact: 

Dr. Orlando Rios, rioso@ornl.gov, 865-574-3747

References: 
  1. Sims, Zachary C., et al. 'Cerium-Based, Intermetallic-Strengthened Aluminum Casting Alloy: High-Volume Co-product Development.' JOM In Press, July 2016.
  2. Sims, Zachary C., et al. 'Characterization of Near Net_Shape Castable Rare Earth Modified Aluminum Alloys for High Temperature Application.' Light Metals (2016): 107-114.
  3. Turchi, PEA, et al. 'Interface between quantum mechanical-based approaches, experiments, and CALPHAD methodology.' CALPHAD 31 (2007): 4-27.
  4. Turchi, PEA, et al. 'From electronic structure to thermodynamics of actinide-based alloys.' JOM 66 (2014): 375-388.
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