Andrèa M. Hodge

Heterogeneous nanostructured materials (HNMs) achieve enhanced strength-ductility combinations through synergistic interactions between microstructurally unique domains. Three hierarchical Inconel 725 coatings with distinctive nanoscale heterogeneous structures are synthesized by magnetron sputtering to investigate how different feature combinations and spatial arrangements collectively influence mechanical properties. Each sample contains multiple cross-sectional domains with varying assemblages of nanotwins, nanocrystalline-equiaxed grains, Cr/Mo-rich carbides, rafted grains, abnormally large grains, and δ-phase, examined via high-resolution nanoindentation mapping with scanning electron microscopy and energy-dispersive X-ray spectroscopy. Results indicate that modulus values fall within expected ranges for Ni-based superalloys, while hardness values reveal pronounced domain-specific contrasts. Specifically, comparing analogous domain property maps across coatings shows that those with Mo-rich carbides exhibit ~ 40% higher hardness in nanocrystalline-equiaxed regions and ~ 23% higher in coarse-grained regions relative to Cr-rich-only counterparts. These findings demonstrate the combined effects from feature-level interactions, precipitate type, surrounding grain structure, and architectural location in hierarchical coatings.

Employing high‐throughput characterization techniques on combinatorially synthesized thin film material libraries offers a pathway for accelerating the discovery and development of novel materials. In particular, nanoindentation is useful for rapidly screening composition‐property relationships. However, despite its widespread use, current literature reveals methodological inconsistencies regarding the number of indents performed per composition and the total number of compositions sampled. This work utilizes a Cu x Ni (1− x ) library as a model system to investigate nanoindentation data collection and optimize experimental throughput. Interpolation methods are applied to data subsets to identify critical regions of interest and capture material trends. The employed framework indicates that characterizing as few as 15% of the total compositions is sufficient for predicting both hardness and modulus trends across the Cu x Ni (1− x ) library. This approach can be used as a baseline for investigating more compositionally complex systems, enabling faster generation of datasets, materials discovery, and training sets for machine learning models.

Nanostructured metallic alloys exhibit an inherently high volumetric density of grain boundaries, which could be stabilized either through kinetic pinning effects, thermodynamic solute enrichment of grain boundaries, or a combination of both. While there have been a multitude of recent strides identifying candidate systems for realizing stable nanocrystalline grain structures, experimental literature often relies on indirect evidence that is supplemented by computational models to ascertain fundamental stabilization mechanisms. This work investigates solute behavior in annealed Fe-W and Fe-Zr alloys through the lens of competing solute segregation and oxide precipitation. Ultimately, the absolute difference between enthalpies of segregation and oxide formation was demonstrated as a useful qualitative metric for evaluating nanocrystalline systems for potential grain boundary enrichment. The importance of high-resolution characterization is underscored, as seemingly thermodynamic stabilization can be easily convoluted with kinetically pinning features at the nanoscale.

Aperiodicity in ceramic nanomultilayers (NMs) has been shown to improve coating functionality, namely, for optimized optical behavior, while the effects of aperiodic layer thicknesses on mechanical deformation remain poorly understood. In this article, the relationships between individual layer thicknesses, optical transmittance, and mechanical behavior are investigated for AlN/Al 2 O 3 , YSZ/Al 2 O 3 , and AlN/YSZ nanomultilayered coatings. These NMs are synthesized with aperiodic layer configurations from individual constituents selected for their optical constants, elastic modulus, and hardness values; the layer designs of select samples are optimized to achieve a transmittance exceeding 90% across the ultraviolet, visible, and near‐infrared spectral range. The effect of aperiodicity on the mechanical properties and deformation is explored at various length scales via nanoindentation, micropillar splitting, and Vickers microindentation. However, competing factors, such as interface type and local microstructure, also play critical roles. It is observed that layer composition strongly influences fracture toughness, as samples with amorphous Al 2 O 3 layers and crystalline/amorphous interfaces exhibit superior mechanical performance and the highest fracture toughness values. Yet, distinct failure modes, including delamination and intergranular fracture, across the different nanomultilayered architectures highlight the relation of optical and mechanical properties to local volume fractions within aperiodic layer stacks and interface characteristics in the coating design.

Abstract Additively manufactured (AM) alloys such as laser powder bed fusion (LPBF) Inconel 718 often exhibit inferior high-temperature mechanical performance compared to their conventionally manufactured (CM) counterparts, in part due to impurity embrittlement. While compositional tailoring has been employed in CM alloys to mitigate impurity effects, this strategy remains largely unexplored in AM materials. In this study, a modified LPBF IN718 was developed by adding trace amounts of Zr, Hf, Mg, and Ca, to address impurity-related degradation (such as sulfur embrittlement) and the performance gap between CM and AM Ni-based superalloys. Ambient tensile tests and high-temperature (650 °C, 704 °C) creep tests were conducted to evaluate the modified alloy relative to standard LPBF IN718. While the modified alloy showed a slight reduction in tensile strength, it demonstrated improved ductility at room temperature and enhanced creep strength, ductility, and rupture life at elevated temperatures. Microstructural analysis using SEM, EDS, EBSD, STEM, and NanoSIMS revealed key differences between the alloys. In the standard alloy, sulfur segregated at alumina particles within grains and at grain boundaries (GB). In contrast, alumina was not detected in the modified alloy, which exhibited a higher fraction of carbides, likely influenced by the trace additions and contributed to the improved mechanical performance. Additionally, the formation of sulfo-carbides and sulfides likely stabilized sulfur, reducing its GB segregation and enhancing GB cohesion, thereby improving creep behavior. Graphical abstract

Insulating materials featuring ultralow thermal conductivity for diverse applications also require robust mechanical properties. Conventional thinking, however, which correlates strong bonding with high atomic-vibration-mediated heat conduction, led to diverse weakly bonded materials that feature ultralow thermal conductivity and low elastic moduli. One must, therefore, search for strongly-bonded single crystals in which heat transport is impeded by other means. Here, we report intrinsic, glass-like, ultralow thermal conductivity and ultrahigh elastic-modulus/thermal-conductivity ratio in single-crystalline Ruddlesden-Popper Ban+1ZrnS3n+1, n = 2, 3, which are derivatives of BaZrS3. Their key features are strong anharmonicity and intra-unit-cell rock-salt blocks. The latter produce strongly bonded intrinsic superlattices, impeding heat conduction by broadband reduction of phonon velocities and mean free paths and concomitant strong phonon localization. The present study initiates a paradigm of “mechanically stiff phonon glasses”. Here, the authors report on the thermal and mechanical properties of Ruddlesden-Popper phases (Ban+1ZrnS3n+1, n = 2 and 3) of a perovskite chalcogenide (BaZrS3) that push to extreme limits and defy the century-old relation between thermal conductivity and interatomic bond strength.

Powder X‐ray diffraction (pXRD) experiments are a cornerstone for materials structure characterization. Despite their widespread application, analyzing pXRD diffractograms still presents a significant challenge to automation and a bottleneck in high‐throughput discovery in self‐driving labs. Machine learning promises to resolve this bottleneck by enabling automated powder diffraction analysis. A notable difficulty in applying machine learning to this domain is the lack of sufficiently sized experimental datasets, which has constrained researchers to train primarily on simulated data. However, models trained on simulated pXRD patterns showed limited generalization to experimental patterns, particularly for low‐quality experimental patterns with high noise levels and elevated backgrounds. With the Open Experimental Powder X‐ray Diffraction Database (opXRD), we provide an openly available and easily accessible dataset of labeled and unlabeled experimental powder diffractograms. Labeled opXRD data can be used to evaluate the performance of models on experimental data and unlabeled opXRD data can help improve the performance of models on experimental data, for example, through transfer learning methods. We collected 92,552 diffractograms, 2179 of them labeled, from a wide spectrum of material classes. We hope this ongoing effort can guide machine learning research toward fully automated analysis of pXRD data and thus enable future self‐driving materials labs.

Over the past three decades, nanoindentation has continuously evolved and transformed the field of materials mechanical testing. Once highlighted by the groundbreaking Oliver-Pharr method, the utility of nanoindentation has transcended far beyond modulus and hardness measurements. Today, with increasing challenges in developing advanced energy generation and electronics technologies, we face a growing demand for accelerated materials discovery and efficient assessment of mechanical properties that are coupled with modern machine learning-assisted approaches, most of which require robust experimental validation and verification. To this end, nanoindentation finds its unique strength, owing to its small-volume requirement, of fast-probing and providing a mechanistic understanding of various materials. As such, this technique meets the demand for rapid materials assessment, including semiconductors, ceramics, and thin films, which are integral to next-generation energy-efficient and high-power electronic devices. Here, we highlight modern nanoindentation strategies using novel experimental protocols outlined by the use of nanoindentation for characterizing functional structures, dislocation engineering, high-speed nanoindentation mapping, and accelerating materials discovery via thin-film libraries. We demonstrate that nanoindentation can be a powerful tool for probing the fundamental mechanisms of elasticity, plasticity, and fracture over a wide range of microstructures, offering versatile opportunities for the development and transition of functional materials. Graphical abstract: Modern strategies for nanoindentation in electronic systems, functional ceramics, heterogeneous structures, and thin films.

• Combinatorial synthesis of an Fe-W material library via magnetron sputtering. • Screened material library via high-throughput X-ray and electron microscopy techniques. • Deconvoluted and quantified composition and growth rate effects on film microstructure. • Coatings exhibit growth rate effects after annealing induced recrystallization. • Growth regimes in material libraries can be tailored via synthesis parameters. Combinatorial magnetron sputtering has been implemented to synthesize compositionally graded thin film material libraries, enabling rapid exploration of structure–property trends via high-throughput characterization techniques. In this study, an Fe-W material library with 169 unique samples is sputter-deposited to investigate the amorphous-crystalline transition across the Fe – 9.4 to 45.5 at.% W range. X-ray diffraction and electron microscopy techniques reveal trends in film microstructure and morphology that are intrinsically connected to alloy composition but further shown to be dependent on synthesis conditions by decoupling composition and thickness/deposition rate effects. Samples are classified into three distinct regimes: crystalline, mixed-mode, or X-ray amorphous. By deconvoluting and analyzing the interplay between composition and deposition rate, it is shown that growth kinetics can sufficiently alter phase formation to dominate compositionally driven mechanisms within a single material library. This observation is verified after heat-treatment to 750 °C on selected samples. Particularly within the mixed-mode regime, the relationship between solute content and deposition rate is quantified, thereby enabling the tailoring of materials libraries investigations of composition and growth rate effects. Overall, this work combines the expansive compositional space in a combinatorial library with sputtering science to identify microstructural and phase regime boundaries in the Fe-W system.

Abstract In this study, a combinatorial and high-throughput approach was leveraged to investigate nanotwin behavior in the ternary CuNiAl alloy system. Combinatorial co-sputtering was used to synthesize 169 unique CuNiAl alloy compositions, which were characterized in both the as-sputtered and annealed conditions to elucidate relationships between composition, nanotwin formation, and phase evolution. Compositional effects on phase formation were investigated using high-throughput X-ray diffraction, while scanning transmission electron microscopy was used to identify nanotwin compositional boundaries and isolate the roles of varied composition and nanotwin formation on microstructural evolution. It was determined that Al content was the primary variable influencing thermal evolution in the nanotwinned CuNiAl alloys, as it altered the thermodynamic driving forces by changing composition and reducing the as-sputtered twin boundary spacing. Overall, this work demonstrates a novel approach to globally study unexplored nanotwin synthesis domains beyond binary alloys. Graphical Abstract

High-temperature creep tests of additively manufactured (AM) and wrought nickel alloy 718 (IN718) were conducted at 650 °C and 704 °C at stresses ranging from 316 to 819 MPa. The AM alloy had a greater creep strength than the wrought alloy at nearly all testing conditions due to increased volume fractions of γ” in the matrix and carbides at grain boundaries; however, the creep rupture ductility of the AM material was significantly reduced at all testing conditions. Secondary ion mass spectrometry (SIMS) revealed that sulfur segregation, resulting from a lack of Mg in the AM alloy, is the most plausible explanation for the observed ductility loss in AM IN718. Overall, this work focuses on understanding and defining the mechanism of embrittlement in AM IN718.

Multiperspective frameworks, such as the social relations model, socioanalytic theory, the realistic accuracy model, the self-other knowledge asymmetry model, and the trait-reputation-identity model, have advanced understanding of personality over the last 40 years. Due to a resurgence of interest in multiperspective research on personality and other constructs in organizational psychology, we conducted an integrative conceptual review of these specific multirater frameworks and their application in work settings. Our review identifies similarities and differences in these frameworks and suggests that they collectively represent an invaluable resource for personality researchers and the broader field of organizational psychology. Through our review, we distinguish multiperspective frameworks from similar approaches (e.g., multirater designs), track the evolution of these frameworks, and leverage current applications of these frameworks to craft a future research agenda. Our review serves as a roadmap to help scholars apply multiperspective logic more thoroughly and systematically in personality research and beyond. We close with a discussion of practical implications. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

This study examines the synthesis of growth nanotwins in CuNi alloys using combinatorial and high-throughput experimental techniques. 338 unique CuNi samples were synthesized via co-sputtering to create a material library encompassing composition, hardness, phase, and crystallographic data. The material library data in conjunction with scanning transmission electron microscopy was used to evaluate growth twinning over a wide compositional range (Cu – 6.8 to 58.8 at% Ni). A direct correlation between measured twin boundary spacings and the stacking fault energies underscored limitations of the current growth twin model caused by an underestimation of the free energy penalty for forming non-twinned grains. To address this, a refined model was developed to accurately capture the variation in twin boundary spacing and formation across all compositions. This model paves the way for high-throughput investigations into nanotwin synthesis in various alloy systems.

The thermal stability of crystalline-amorphous interfaces was investigated in Fe/FeW nanomultilayers (NMs), where the alloy layers were amorphous in the as-sputtered state with concentrations of Fe-38 at.% W or Fe-67 at.% W. Compositionally driven devitrification, layer breakdown, and recrystallization were compared using both single-layer and multilayer configurations at temperatures ranging from 250 °C to 750 °C. Annealing of the NMs to 500 °C revealed destabilization in the Fe-67 W layers with the formation of crystalline-crystalline interfaces (CCIs) whereas the Fe-38 W layers remained intact with stable crystalline-amorphous interfaces (CAIs). Further annealing to 750 °C resulted in multilayer evolution and recrystallization, where breakdown of the CAIs was attributed to layer intermixing while the CCIs experienced intermetallic grooving and pinch-off. The influence of amorphous stability, composition, and intermetallic formation are discussed with respect to the NM breakdown mechanisms. This work highlights a promising strategy for exploring compositionally driven stability at the nanoscale in crystalline-amorphous alloys.

In this work, magnetron sputtering coupled with a heat treatment is demonstrated as a route to obtain surrogate microstructures comparable to those achieved by laser‐based additive manufacturing (AM) for Ni superalloys. Furthermore, this technique is shown to be a novel and efficient way of screening elemental additions with high compositional resolution for AM, without the need for designing and characterizing custom‐atomized powders. Herein, Inconel 718 films are sputtered from both arc‐melted and AM targets to capture any compositional changes and to develop a comprehensive methodology. Films are characterized via electron microscopy techniques to establish similarities between sputtered plus heat‐treated films and bulk AM Inconel 718 microstructures reported in literature. Since Inconel 718 is susceptible to high‐temperature S embrittlement, films were then co‐sputtered with small amounts of Zr or Hf, which are found to facilitate sulfur segregation via nano secondary ion mass spectrometry analysis. Overall, this work highlights how magnetron sputtering plus heat treatment can be leveraged to rapidly screen novel AM microstructures, thereby accelerating the development and deployment of AM materials.

Abstract The role of interfaces and the controlling synthesis parameters of graded dealloyed nanoporous metallic materials are investigated, focusing on the dealloying front progression in complex precursor materials with multiple alloy compositions. Specifically, the effects of relative density and chemical potential on the dealloying front in sputtered bilayer copper alloy films are explored with two case studies: Cu–Al/Cu–Al and Cu–Al/Cu–Zn. Cross-sectional scanning electron (SEM) micrographs and energy-dispersive X-ray spectroscopy mapping trace the dealloying front across three time intervals, while top-surface and cross-sectional SEM probes the final dealloyed foam morphology. Final ligament sizes were found to be independent of the synthesis parameters (21–28 nm), due to a combination of fast reaction times and phosphate-inhibited surface diffusion of Cu atoms. The chemical potential gradient yielded faster reaction times, whereas slower reaction times and a higher at.% of Cu in the top layer of precursor material produced a more uniform morphology. Graphical abstract

Multifunctional optical nanomultilayers (NMs) are needed for a wide array of applications, ranging from optical windows to electronic screens. Since the individual material constituents in optical coatings are often selected only for their desirable optical properties, mechanical characterization of the optical nanomultilayers is typically limited. Here, AlN/SiO2, TiO2/SiO2, and AlN/Al2O3 nanomultilayers synthesized in non-optimized and optimized optical performance layer configurations are tested using microtensile, nanoindentation, and pillar splitting techniques to highlight the effects of optical optimization on mechanical performance. Trends within each type of test and across all deformation modes reveal that layer thickness, volume fraction, and interfacial crystallinity can be viewed as controlling features for optical and mechanical performance, although their correlation may vary. It was observed that both configurations of the AlN/Al2O3 NMs exhibit the highest mechanical performance across all three testing techniques with an average experimental transmittance of 93.8% for the optimized layer configuration. Overall, the results from this expanded view of mechanical properties in ceramic optical nanomultilayers suggest the possibility of tuning film characteristics for joint optimization of opto-mechanical nanomultilayered coatings.

In this work, four distinct heterogeneous nanostructured Inconel 725 films synthesized via magnetron sputtering, feature an extensive array of nanodomains including abnormally large grains, heterogeneous precipitation, rafted structures, and both growth and annealing nanotwins. By leveraging the substrate type used during deposition, films with different stress profiles were produced, resulting in fully nanotwinned films with either coarse or fine grain widths in the as-prepared state, and heterogeneous nanostructured films with either a uniform or gradient feature size distribution after heat treatment. Thorough microstructural characterization was used to identify the types of nanodomains in each sample. The type of microstructure produced was found to have important consequences on mechanical behavior and plastic deformation. These findings provide insight on how to alter the distribution of nanodomains, as well as how their arrangement and interactions can affect deformation behavior in heterogeneous nanostructured Ni-superalloys.

Abstract The effect of target geometry on coating microstructure and morphology is correlated to changes in deposition conditions, plasma characteristics, and film growth during planar and hollow cathode sputtering. The sputtering plasma properties for the two target geometries were characterized via Langmuir probe analysis as a function of power density and Ar pressure to determine the evolution of ion density for each configuration. Films were then synthesized at the low (0.4 W cm −2 ) and high (1.2 W cm −2 ) power densities and characterized using x-ray diffraction, scanning electron microscopy, and electron backscatter diffraction to link changes in texturing, morphology, and microstructure with variations in ion density and sputtering deposition conditions caused by target geometry. It was observed that varying target geometry led to an over threefold increase in deposition rate, homologous temperature, and ion density, which altered the morphology and texture of the film without significant changes to the grain size.