Making sustainable aluminum by recycling scrap: The science of “dirty” alloys

The development of strong-scaling computational tools for high-throughput methods with an open-source code and transparent metadata standards has successfully transformed many computational materials science communities While such tools are mature already in the condensed-matter physics community, the situation is still very different for many experimentalists Atom probe tomography (APT) is one example This microscopy and microanalysis technique has matured into a versatile nano-analytical characterization tool with applications that range from materials science to geology and possibly beyond Here, data science tools are required for extracting chemo-structural spatial correlations from the reconstructed point cloud For APT and other high-end analysis techniques, post-processing is mostly executed with proprietary software tools, which are opaque in their execution and have often limited performance Software development by members of the scientific community has improved the situation but compared to the sophistication in the field of computational materials science several gaps remain This is particularly the case for open-source tools that support scientific computing hardware, tools which enable high-throughput workflows, and open well-documented metadata standards to align experimental research better with the fair data stewardship principles To this end, we introduce paraprobe, an open-source tool for scientific computing and high-throughput studying of point cloud data, here exemplified with APT We show how to quantify uncertainties while applying several computational geometry, spatial statistics, and clustering tasks for post-processing APT datasets as large as two billion ions These tools work well in concert with Python and HDF5 to enable several orders of magnitude performance gain, automation, and reproducibility

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On strong-scaling and open-source tools for analyzing atom probe tomography data

Deformation Twinning Versus Slip in Ni-Based Alloys, Containing Pt2Mo-Structured, Ni2Cr-Typed Precipitates

Atom probe tomography (APT) has matured to a versatile nanoanalytical characterization tool with applications that range from materials science to geology and possibly beyond. Already, well over 100 APT microscopes exist worldwide. Information from the APT data requires a post-processing of the reconstructed point cloud which is realized via basic implementations of data science methods, mostly executed with proprietary software. Limitations of the software have motivated the APT community to develop supplementary post-processing tools to cope with increasing method complexity and higher quality demands: examples are how to improve method transparency, how to support batch processing capabilities, and how to document more completely the methods and computational workflows to better align with the FAIR data stewardship principles. 
One gap in the APT software tool landscape has been a collection of open tools which support scientific computing hardware. Here, we introduce PARAPROBE, an open source, efficient tool for the scientific computing of APT data. We show how to process several computational geometry, spatial statistics, and clustering tasks performantly for datasets as large as two billion ions. Our parallelization efforts yield orders of magnitude performance gains and deliver batch processing capabilities. We contribute these tools in an effort to open up APT data mining and simplify it to make tools for rigorous quantification, sensitivity analyses, and cross-method benchmarking available to practitioners.

On Strong Scaling and Open Source Tools for Analyzing Atom Probe Tomography Data

Microcantilever Fracture Tests on Eutectic NiAl‐Cr(Mo) in‐situ Composites

Combining Experiments and Atom Probe Tomography-Informed Simulations on γ′ Precipitation Strengthening in the Polycrystalline Ni-Base Superalloy A718Plus

This study demonstrates metal fused filament fabrication (MF3) as an alternative additive and highly flexible manufacturing method for free-form fabrication of high-performance alloys. This novel processing, which is similar to Metal injection molding (MIM), enables a significant reduction in manufacturing costs for complex geometries, since expensive machining can be avoided. Utilizing existing equipment and reducing material expense, MF3 can pave the way for new and low-cost applications of IN 718, which were previously limited by high manufacturing costs. Iterative process optimization is used to find the most suitable MF3 process parameters. High relative density above 97% after pressureless sintering can be achieved if temperature profiles and atmospheres are well adjusted for thermal debinding and sintering. In this study, the influence of processing parameters on the resulting microstructure of MF3 IN 718 is investigated. Samples sintered in vacuum show coarse-grained microstructure with an area fraction of 0.36% NbC at grain boundaries. Morphology and composition of formed precipitates are analyzed using transmission electron microscopy and atom probe tomography. The γ/γ″/γ' phases' characteristics for IN 718 were identified. Conventional heat treatment is applied for further tailoring of mechanical properties like hardness, toughness and creep behavior. Fabricated samples achieve mechanical properties similar to MIM IN 718 presented in literature. 

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Metal fused filament fabrication of the nickel-base superalloy IN 718

Eutectic NiAl-(Cr,Mo) composites are promising high temperature materials due to their high melting point, excellent oxidation behavior and low density. To enhance the strength, hardness and fracture toughness, high cooling rates are beneficial to obtain a fine cellular-lamellar microstructure. This can be provided by the additive process of selective electron beam melting. The very high temperature gradient achieved in this process leads to the formation of the finest microstructure that has ever been reported for NiAl-(Cr,Mo) in-situ composites. A very high hardness and fracture toughening mechanisms were observed. This represents a feasibility study towards additive manufacturing of eutectic NiAl-(Cr,Mo) in-situ composites by selective electron beam melting.

Nanoscaled eutectic NiAl-(Cr,Mo) composites with exceptional mechanical properties processed by electron beam melting.

Correlation Between Local Chemical Composition and Formation of Different Types of Ordered Phases in the Polycrystalline Nickel-Base Superalloy A718Plus

Laser cladding of superalloys provides an attractive and cost‐efficient technique for near‐net shape manufacturing, remanufacturing, or individualized repair of components. While the weldability of γ' hardened Ni‐base superalloys is limited, Co‐base superalloys should have a lower susceptibility for cracking during welding due to a lower γ' solvus temperature and less segregation than Ni‐base superalloys. The weldability of the Co‐base superalloy CoWAlloy2Mod and the resulting mechanical properties at 950 °C are investigated. In the as‐welded condition of CoWAlloy2Mod, a fine dendritic microstructure without forming cracks and limited porosity is found. After a three‐step heat treatment, recrystallized, equiaxed grains and a high γ' volume fraction are obtained leading to a very good strength. CoWAlloy2Mod shows a significantly higher strength and creep strength than the conventional weld filler Co‐alloy PWA795.

Andreas Förner

Papers

Combining Experiments and Atom Probe Tomography-Informed Simulations on γ′ Precipitation Strengthening in the Polycrystalline Ni-Base Superalloy A718Plus

Metal fused filament fabrication of the nickel-base superalloy IN 718

Nanoscaled eutectic NiAl-(Cr,Mo) composites with exceptional mechanical properties processed by electron beam melting.

Correlation Between Local Chemical Composition and Formation of Different Types of Ordered Phases in the Polycrystalline Nickel-Base Superalloy A718Plus

Crack‐Free Welding of a Co‐Base Superalloy with High γ' Precipitate Fraction