The Materials Genome Initiative (MGI) seeks to accelerate the discovery, design, development, and deployment of new materials through the creation of a materials innovation infrastructure. This infrastructure is essentially a system for providing data and tools that encapsulate our existing knowledge about materials, and the means to create new knowledge. Given this approach, MGI is also deeply linked to the ongoing exponential growth in applications of machine learning and artificial intelligence (AI) to materials research. This article explores the connections between MGI, the consequent need for data publication, the implications for data-driven science, and the application of AI to materials design. Examples will demonstrate how materials research is transforming in remarkable ways, and that the MGI vision of accelerated materials discovery is within reach.

In this work, a high-temperature low-cycle fatigue (LCF) behavior of a newly developed austenitic oxide dispersion strengthened (ODS) steel is investigated. The LCF tests were performed in air at 650 °C under three different strain amplitudes (±0.4, ±0.5, and ±0.7%) with a nominal strain rate of 10−3 s−1. The measured cyclic stress response showed four distinct stages which include short initial stable cyclic response followed by a prolonged hardening with subsequent short saturation and finally crack initiation and growth stage. The rate of hardening and the duration of stages are a function of applied strain amplitude. Microstructural investigations were carried out to shed light on the deformation mechanisms. After cycling, the overall microstructure appears stable without any modifications in grain shape and size. In addition, twinning and stacking fault fractions remain unchanged. However, cyclic hardening is an aftermath of dislocation multiplication whose rate is also a function of applied strain amplitude. Furthermore, oxide particles, as well as fine grains, inhibit strain localization by restricting three-dimensional dislocation structure formation that are associated with the development of extrusions and intrusions and are readily observed in conventional austenitic non-ODS steels.

Synthetic photonic materials created by engineering the profile of refractive index or gain/loss distribution, such as negative-index metamaterials or parity-time-symmetric structures, can exhibit electric and magnetic properties that cannot be found in natural materials, allowing for photonic devices with unprecedented functionalities. In this article, we discuss two directions along this line—non-Hermitian photonics and topological photonics—and their applications in nonreciprocal light transport when nonlinearities are introduced. Both types of synthetic structures have been demonstrated in systems involving judicious arrangement of optical elements, such as optical waveguides and resonators. They can exhibit a transition between different phases by adjusting certain parameters, such as the distribution of refractive index, loss, or gain. The unique features of such synthetic structures help realize nonreciprocal optical devices with high contrast, low operation threshold, and broad bandwidth. They provide promising opportunities to realize nonreciprocal structures for wave transport.

This article discusses recent studies of on-chip integration of a plasmonic isolator on a Si substrate and a hybrid isolator on an InP substrate. The key characteristics of the plasmonic isolator are reviewed and future prospects are discussed. A method to enhance the magneto-optical figure of merit (FOM) and reduce the propagation loss of a surface plasmon in order to realize the proposed design of the plasmonic isolator is described. One hundred percent enhancement of the FOM and 20× reduction of propagation loss in the optimized ferromagnetic plasmonic structure are experimentally demonstrated.

Optical isolators, devices that only allow unidirectional light propagation, constitute an essential building block for photonic integrated circuits. For near-infrared communications wavelengths, most current isolator designs rely on the incorporation of magneto-optical (MO) materials to break time-reversal symmetry, such as iron garnets or magnetically substituted semiconductors. MO garnets form the backbone of traditional bulk isolators, but suffer from large lattice and thermal mismatch with common semiconductor substrates, which has significantly impeded their integration into on-chip optical isolators. Materials innovations over the past few years have overcome these barriers and enabled monolithic deposition of MO oxide thin films on silicon using techniques such as pulsed laser deposition and magnetron sputtering. On-chip optical isolator devices with polarization diversity in the telecommunication band have been demonstrated based on these materials. This article reviews the latest technological breakthroughs in MO oxide material growth as well as device design and integration strategies toward practical implementation of on-chip optical isolation.

In this work, morphology, viability, and metabolism of the amniotic mesenchymal stem cells conditioned with different citric acid (CA)/media ratios were investigated using rhodamine-phalloidin/4′,6-diamidino-2-phenylindole staining, live/dead assay, proliferating cell nuclear antigen, and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL assay). The cells cultured in 25:75 CA/media displayed well spread actin filaments with a prominent nucleus and evidenced optimum viability. The gelation kinetics of chitosan solution in CA/media (25:75) was monitored via dynamic time sweep analysis on a rheometer. The chemical cross-linking of chitosan with CA was confirmed by nuclear magnetic resonance studies. Subsequently, chitosan solution was extruded in CA/media bath containing cells under benign conditions to form cell-laden fibers (living fibers). The prelabeled cells imaged immediately after fiber formation confirmed the attachment of the cells on the fibers. This approach has several advantages including instantaneous gelation, tunable mechanical properties, and adjustable biodegradability that can provide a platform technology for creating viable three dimensional (3D) building blocks for tissue engineering applications.

Metal–resin interpenetrating phase composites (IPCs) have been produced by spontaneously infiltrating unsaturated polyester resin into porous stainless steel fibrous preforms under vacuum conditions. The compressive behaviors of the IPCs were investigated and the fractures were examined. The compressive strength and elastic modulus increase with increasing fiber fraction. The structures, compressive behaviors, and energy absorption capacities of the IPCs exhibit anisotropy. A higher compressive strength, lower elastic modulus, and lower energy absorption efficiency are observed in the through-thickness direction. The energy absorption efficiency slightly decreases with increasing fiber fraction in a certain range rather than monotonically increasing or decreasing. The energy absorption efficiency in the in-plane direction is superior to that in the through-thickness direction. Finer fibers improve the strength and elastic modulus but have little influence on the energy absorption efficiency. Resin collapse, fiber necking, and debonding are the main failure types observed in the composites.

The use of the advanced manufacturing technique of strain annealing for nanocomposite magnetic ribbons enables control of relative permeabilities and spatially dependent permeability profiles. Tuned permeability profiles enable enhanced control of the magnetic flux throughout magnetic cores, including the concentration or dispersion of the magnetic flux over specific regions. Due to the correlation between local core losses and temperature rises with the local magnetic flux, these profiles can be tuned at the component level for improved losses and reduced steady-state temperatures. We present analytical models for a number of assumed permeability profiles. This work shows significant reductions in the peak temperature rise with overall core losses impacted to a lesser extent. Controlled strain annealing profiles can also adjust the location of hotspots within a component for optimal cooling schemes. As a result, magnetic designs can have improved performance for a range of potential operating conditions.

The powder-bed laser additive manufacturing (AM) process is widely used in the fabrication of three-dimensional metallic parts with intricate structures, where kinetically controlled diffusion and microstructure ripening can be hindered by fast melting and rapid solidification. Therefore, the microstructure and physical properties of parts made by this process will be significantly different from their counterparts produced by conventional methods. This work investigates the microstructure evolution for an AM fabricated AlSi10Mg part from its nonequilibrium state toward equilibrium state. Special attention is placed on silicon dissolution, precipitate formation, collapsing of a divorced eutectic cellular structure, and microstructure ripening in the thermal annealing process. These events alter the size, morphology, length scale, and distribution of the beta silicon phase in the primary aluminum, and changes associated with elastic properties and microhardness are reported. The relationship between residual stress and silicon dissolution due to changes in lattice spacing is also investigated and discussed.

Wollastonite (CaSiO3)–diopside (CaMgSi2O6) glass-ceramic scaffolds have been successfully fabricated using two different additive manufacturing techniques: powder-based 3D printing (3DP) and digital light processing (DLP), coupled with the sinter-crystallization of glass powders with two different compositions. The adopted manufacturing process depended on the balance between viscous flow sintering and crystallization of the glass particles, in turn influenced by the powder size and the sensitivity of CaO–MgO–SiO2 glasses to surface nucleation. 3DP used coarser glass powders and was more appropriate for low temperature firing (800–900 °C), leading to samples with limited crystallization. On the contrary, DLP used finer glass powders, leading to highly crystallized glass-ceramic samples. Despite the differences in manufacturing technology and crystallization, all samples featured very good strength-to-density ratios, which benefit their use for bone tissue engineering applications. The bioactivity of 3D-printed glass-ceramics after immersion in simulated body fluid and the similarities, in terms of ionic releases and hydroxyapatite formation with already validated bioactive glass-ceramics, were preliminarily assessed.

In this work, the deformation mechanisms underlying the room temperature deformation of the pseudomorphic body centered cubic (BCC) Mg phase in Mg/Nb nanolayered composites are studied. Nanolayered composites comprised of 50% volume fraction of Mg and Nb were synthesized using physical vapor deposition with the individual layer thicknesses h of 5, 6.7, and 50 nm. At the lower layer thicknesses of h = 5 and 6.7 nm, Mg has undergone a phase transition from HCP to BCC such that it formed a coherent interface with the adjoining Nb phase. Micropillar compression testing normal and parallel to the interface plane shows that the BCC Mg nanolayered composite is much stronger and can sustain higher strains to failure than the HCP Mg nanolayered composite. A crystal plasticity model incorporating confined layer slip is presented and applied to link the observed anisotropy and hardening in the deformation response to the underlying slip mechanisms.