Designing ductile materials for extreme environments such as fusion reactors requires a deep understanding of the complex interplay between electronic structure, mechanical stability, and wide compositional space. In this work, we introduce DuctGPT, a physics-informed, GPT-powered machine learning platform that enables rapid and accurate prediction of ductility across a wide range of refractory multi-principal element alloys (MPEAs). Trained on both experimental and high-fidelity computational data, DuctGPT integrates descriptors such as density of states at the Fermi level, elastic constants, and valence electron concentration to capture the fundamental mechanisms governing ductile versus brittle behavior. Using this framework, we screen over 1,000 compositions in of body-centered cubic (BCC) MPEAs, including two new alloy classes, i.e., NbTa-rich (NbTa >50 at.%) NbTa-Ti-V and W-rich (> 50 at.%) W-Ti-V MPEAs, to rapidly identify promising alloy compositions with enhanced ductility. Validation against experimental data confirms the model's ability to predict ductility with high fidelity and low uncertainty. By leveraging conversational AI and robust physical modeling, DuctGPT provides a blueprint for the next generation of alloy design assistants, enabling human-AI collaboration in the accelerated discovery of ductile, high-performance materials for fusion, aerospace, and advanced manufacturing.

The composition Al-16Ce-1Mg has been developed as a dedicated alloy for processing by laser powder bed fusion (LPBF). Guided by thermodynamic considerations and exploiting the unique conditions during LPBF, the strongly hypereutectic alloy features nm-scale aluminum dendrites reinforced by a continuous intermetallic network. The unique temperature stability of Al-Ce alloys as well as the microstructure topology and scale grant the alloy high strength in as-printed state with excellent thermal stability. The superior mechanical properties of the continuously reinforced nanocomposite were established by comparison with the spheroidized, microstructure of similar scale.

The metallurgy and materials communities have long understood and exploited fundamental links between chemical and structural ordering in metallic solids to tailor their mechanical properties. We extend these ideas to include prediction of the nanocrystalline strength limit in high-entropy alloys and intermetallic compounds, where a breakdown occurs in the classical Hall-Petch strengthening behavior. The highest reported strength achievable through alloying has rapidly climbed and given rise to new classifications of materials with extraordinary properties, with a notable case being nanocrystalline metals. High-entropy alloys (chemically disordered, concentrated solid solutions) and intermetallic compounds are two boundary cases of how tailored order can be used to manipulate mechanical behavior. Here, we show that the complex electronic-structure mechanisms governing the peak strength of alloys and pure metals can be reduced to a few physically meaningful parameters based on their atomic arrangements and used-with no fitting parameters-to predict the maximum strength of these materials. This includes a generalized energy-based accounting for the degree of structural and chemical ordering that allows for rapid and reasonably accurate prediction of peak strength (validated in the nanocrystalline limit) as a function of temperature. Predictions of maximum strength based on the activation energy (with all materials properties derived from DFT calculations or experiments) for a stress-driven transition to an amorphous state is shown to accurately describe the breakdown in Hall-Petch behavior at the smallest crystallite sizes for pure metals, intermetallic compounds, high-entropy alloys, and metallic glasses. This activation energy is also shown to be directly proportional to interstitial electronic charge density, which is a good predictor of ductility, stiffness (moduli), and phase stability in high-entropy alloys and solid metals generally. The proposed framework suggests the possibility of coupling ordering and intrinsic strength to mechanisms like dislocation nucleation, hydrogen embrittlement, and transport properties, such as through correlations between the activation energies for amorphization with stacking-fault and grain boundary energies. It additionally opens the prospect for greatly accelerated structural materials design and development to address materials challenges limiting more sustainable and efficient use of energy.

Nd-Fe-B based magnets have the highest energy product among all permanent magnets, which is required for numerous clean energy technologies. For higher temperature applications (T > 150°C), additions of heavy rare earth elements (HREEs) such as Dy are required to maintain sufficient coercivity during operation. Additions of Dy are expensive. Thus, it is desirable to reduce the need for HREEs by reducing the grain size to the nanoscale, which increases the coercivity and decreases its temperature dependence. Here, we report a novel nanograin Nd-Fe-B magnet fabrication method that is continuous and inexpensive. The process uses mechanically milled Nd-Fe-B melt-spun flakes as feedstock powder that is packed into a metal vessel and then hot rolled to form a fully dense and highly textured strip magnet with tailored thicknesses, down to 800 µm. Using this process, fully dense nanograin bulk magnets can be synthesized in minutes compared to the traditional multi-step processes that are typically low throughput.

A common limitation of La substitutions into (Nd, La)2Fe14B magnets is the reduction of the anisotropy field (Ha), which decreases magnet coercivity (Hcj). Adding a small amount of Pr-Cu to a La-containing neo magnet may modify the grain boundary (GB), which can help recover a fraction of the degraded Hcj. An optimal GB modification requires a carefully designed post-sinter heat treatment, which is the focus of this work on characterizing the effects of multi-step post-sintering annealing on the evolutions of microstructure and magnetic properties. We find that Nd and Cu concentrations at GBs and triple junctions (TJs) increase when the annealing temperatures are lowered. Annealing temperatures of 580°C and 480°C (near rare-earth-rich eutectic temperatures) enabled the development of a thick and continuous GB phase, which helps to magnetically decouple the grains, and, thus, enhance Hcj. For the alloy with 25

Silver, known for its high thermal and electrical conductivity, is an ideal metal for thin-film electrode applications. Because alloying can negatively affect conductivity, enhancing the strength and resistance to strain poses a tremendous challenge when applied to pure Ag films. Herein, in both experiments and atomistic simulations, we discover a nanoscale strengthening mechanism by intercalating ultrathin amorphous Ni-rich layers between pure nanocrystalline Ag films, resulting in the formation of a multilayered Ag and Ni-Ag alloy material with a stable grain size (22 nm) combining the highest hardness (2.6 GPa), tensile strength (677 MPa) and plastic elongation (6.6%) ever reported for this metal. The integration of amorphous Ni-Ag alloy nanolayers substantially improves the strain hardening behavior and extends the tensile ductility compared to standard crystalline Ag/Ni nanolaminates at an equivalent Ag layer thickness. This phenomenon results from strain-induced chemical short-range order within the amorphous Ni-Ag nanolayers during plastic deformation. The new nanoscale strengthening mechanism can be easily leveraged to develop nanocrystalline films with exceptional mechanical and physical properties.

The metallurgy and materials communities have long known and exploited fundamental links between chemical and structural ordering in metallic solids and their mechanical properties. The highest reported strength achievable through the combination of multiple metals (alloying) has rapidly climbed and given rise to new classifications of materials with extraordinary properties. Metallic glasses and high-entropy alloys are two limiting examples of how tailored order can be used to manipulate mechanical behavior. Here, we show that the complex electronic-structure mechanisms governing the peak strength of alloys and pure metals can be reduced to a few physically-meaningful parameters based on their atomic arrangements and used (with no fitting parameters) to predict the maximum strength of any metallic solid, regardless of degree of structural or chemical ordering. Predictions of maximum strength based on the activation energy for a stress-driven phase transition to an amorphous state is shown to accurately describe the breakdown in Hall-Petch behavior at the smallest crystallite sizes for pure metals, intermetallic compounds, metallic glasses, and high-entropy alloys. This activation energy is also shown to be directly proportional to interstitial (electronic) charge density, which is a good predictor of ductility, stiffness (moduli), and phase stability in high-entropy alloys, and in solid metals generally. The proposed framework suggests the possibility of coupling ordering and intrinsic strength to mechanisms like dislocation nucleation, hydrogen embrittlement, and transport properties. It additionally opens the prospect for greatly accelerated structural materials design and development to address materials challenges limiting more sustainable and efficient use of energy.

In this work, we have used bulk combinatorial synthesis to rapidly identify a (Nd,Ce,La)-Fe-B composition that is both Nd-lean (<50 % of total rare earth content) and exhibits good thermal stability (TC similar to 269 degrees C). Bulk anisotropic magnets of the corresponding composition [i.e. (Nd0.47Ce0.28La0.25)(2.2)Fe14B1 (at%) + (1.5 wt% TiC)] were synthesized by hot deformation and hot-roll processes. To enhance the energy product of the hot deformed alloys, feedstock powder with 2.5-7.5 wt% Ce-Al-Cu grain boundary modifier was blended together prior to deformation processing. Moreover, hot deformation processing parameters, temperature (T), and processing time (t), were examined over a wide range to enhance the energy product of the resultant magnet alloys. We found that adding just 2.5 wt% Ce-Al-Cu increased the maximum energy product from similar to 12 MGOe for the monolithic alloy to similar to 20 MGOe for the alloy with added grain bounder modifier. The processing parameters (e.g., temperature and time) identified for hot deformation were applied to the hot-rolling process to synthesize samples with larger dimensions that exhibit an energy product of 17.7 MGOe with 5 wt% Ce-Al-Cu added.

Cerium oxide is a low-value byproduct of rare-earth mining yet constitutes the largest fraction of the rare earth elements. The reduction of cerium oxide by liquid aluminum is proposed as an energy- and cost-efficient route to produce high-strength Al-Ce alloys. This work investigated the mechanism of a multi-step reduction reaction to facilitate the industrial adaptation of the process. Differential scanning calorimetry in combination with time-resolved synchrotron diffraction data uncovered the rate-limiting reaction step as the origin of the reported temperature dependence of reduction efficiency. This is the first in situ study of a metallothermic reaction mechanism and will serve as guidance for cost- and energy efficient industrial process control.

Al-Ce-based alloys are promising candidates for additive manufacturing (AM) due to their hot cracking resistance and because they do not require heat treatment to obtain precipitation strengthening. The rapid solidification characteristic of AM can lead to enhanced mechanical properties; however, the strengthening mechanisms over large composition ranges are unclear. Here, combinatorial synthesis by directed-energy deposition (DED) and hardness measurements were used to rapidly map the composition-dependent strength of the ternary Al-Ce-Mg system. Tensile testing and microstructure characterization of selected compositions were performed to elucidate the compositional dependence of the strengthening mechanisms. Al11Ce3 precipitates were present in all cases, and the maximum hardness (1.25 GPa) was measured for the Al-8Ce-10Mg composition. A combination of (i) Hall-Petch strengthening, based on the FCC matrix phase cell size; (ii) precipitation strengthening, based on Al11Ce3 volume fraction and size; and (iii) solid solution strengthening, based on Mg composition of the matrix phase, were used to account for the measured strengths. Hardness is shown to correlate well with ultimate tensile strength in alloys with substantial work-hardening, highlighting the value of surface-based techniques for rapid screening.

First-principles calculations were performed on the interfaces between Al and SiC, which is a widely used strengthening agent in aluminum metal-matrix-composites (Al/MMC). C-terminated interfaces have much larger work of adhesion than Si-terminated interfaces, indicating that the former has much stronger interfacial bonding. The electron localization function shows that the chemical bonding between Al and C has a strong covalent character, while the bonding between Al and Si is largely metallic. As a result of the vastly different chemical bonding, the work of adhesion for C-terminated interfaces increases with the number of dangling bonds at the interface, while the opposite trend was observed for Si-terminated interfaces. Additionally, the interface energy for Si-terminated interfaces is comparable to that for C-terminated interfaces, suggesting both types of terminations can coexist in the Al/SiC system.

Al-Ce-based alloys are promising candidates for additive manufacturing (AM) due to their hot-cracking resistance and because they do not require heat treatment to obtain precipitation strengthening. Rapid solidification rates enabled by AM methods can lead to enhanced mechanical properties; however, the strengthening mechanisms over large composition ranges were unclear. Here, combinatorial synthesis by directed-energy deposition (DED) and hardness measurements were used to rapidly map the composition-dependent strength of the ternary Al-Ce-Mg system. Tensile testing and microstructure characterization of selected compositions were performed to elucidate the compositional dependence of the strengthening mechanisms. Al11Ce3 precipitates were present in all cases, and the maximum hardness (1.25 GPa) was measured for the Al-8Ce-10Mg composition. A combination of (i) Hall-Petch strengthening, based on the FCC-matrix-phase cell size; (ii) particle strengthening, based on Al11Ce3 volume fraction and size; and (iii) solid-solution strengthening, based on Mg composition of the matrix phase, were used to account for the measured strengths. Vickers hardness is shown to correlate well with ultimate tensile strength in these alloys, highlighting the value of surface-based techniques for rapid screening. (C) 2023 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

In this paper, we present the results of computational fluid dynamics (CFD) analysis to assess castability, porosity, molten metal fluidity and other technological properties of a new Al–Ce alloy. A thermodynamic analysis of a new Al–Ce alloy is done to obtain the physical properties as a function of temperature across both solid and liquid phases. These properties are then used to build the CFD model of the full casting process from initial pouring through to final solidification of the part, here an example of a heavy duty MOR mount is used. This process shows that CFD can be used to assess the capability of the alloy to properly fill the mold, as well as give predictions where scattered porosity or large-scale defects may occur in the casting. Unlike the commercially available software (e.g., ProCAST, SOLIDCast, MAGMASOFT ® ) the complex 3D-analysis of the stress/strain fields in cast parts is not performed at this time. The simulation are performed in Star-CCM+ using a volume of fluid analysis. However, the availability of free software for assessing the required thermodynamic/thermo-physical properties of new alloys (OpenCALPHAD) and CFD codes such as OpenFOAM ® makes the developed option attractive and economical to adapt in future, especially for the analysis of new Al–Ce alloys, for which the available data does not exist.

lowering magnetic strength in spite of attempts to grow large textured grains by a stress-biased solid state grain alignment method to convert them to high energy anisotropic magnets. It was hypothesized that oxidation during de-binding in air left many prior particle boundary oxides within the sintered microstructure that hindered grain growth and texturing during the stress-biased texturing procedure and prevented the desired abnormal grain growth (AGG). Here we explored a vacuum de-binding step that was linked (in-place) to vacuum sintering and found that the Co-lean exhibited faster uniform grain growth that doubled the average grain size (40 μm to 80 μm). Linked vacuum de-binding and sintering of Full-Co produced some AGG after only 1 h of 1240°C sintering. A new direction for promoting AGG (and stress-biased texturing) in alnico is being explored that utilizes a fundamental analysis of systems with second phase particles that either inhibit or boost grain growth. This effort explores the influence of vacuum de-binding linked to a series of lower sintering temperatures at a fixed time (4h) to see if oxide particle size and volume fraction can be changed to promote AGG conditions in alnico. Surprising qualitative results indicate that AGG may be promoted for vacuum sintering at less than 1200°C.