Phase identification is an arduous task during high-throughput processing experiments, which can be exacerbated by the need to reconcile results from multiple measurement techniques to form a holistic understanding of phase dynamics. Here, we demonstrate AutoPhase, a machine learning algorithm, which can identify the presence of the different phases in spectral and diffraction data. The algorithm uses training data to determine the characteristic features of each phase present and then uses these features to evaluate new spectral and diffraction data. AutoPhase was used to identify oxide phase growth during a high-throughput oxidation study of NiAl bond coats that used x-ray diffraction, Raman, and fluorescence spectroscopic techniques. The algorithm had a minimum overall accuracy of 88.9% for unprocessed data and 98.4% for postprocessed data. Although the features selected by AutoPhase for phase attribution were distinct from those of topical experts, these results show that AutoPhase can substantially increase the throughput high-throughput data analysis.

This study presents an analytical model of the reflectance of flat and textured silicon substrates. The model was used to study the reflection behavior of textured silicon surfaces under non-normal incidence. By characterizing the incident light and facets of the silicon wafer with vector geometry, dot products and Phong's reflection model (https://cs.oberlin.edu/∼bob/cs357.08/VectorGeometry/VectorGeometry.pdf) were used to determine the reflection angles between incident light rays and pyramidal facets. The possible optical interactions are considered for a wide range of pyramidal geometries and light incidence angles that are relevant to the exposure of textured silicon surfaces to incident sunlight. Furthermore, the model was used to investigate the possibility of secondary reflection, for the full range of incidence angles to the substrate. The textured silicon surfaces were found to reduce the reflection angles more effectively than flat substrates at lower angles of incidence. Secondary reflection was also found to be experienced or guaranteed, for all pyramid heights, when the angle of incidence to the substrate was less than 19.4°. The predictions are validated with experimental measurements of reflectance from (001)-textured silicon surfaces. The implications of the results are then discussed for the development of micropyramids for improved photoconversion in silicon solar cells.

The dynamic recrystallization (DRX) behavior of Ni–18.3Cr–6.4Co–5.9W–4Mo–2.19Al–1.16Ti superalloy was investigated by means of isothermal compression tests in the temperature range of 1010–1160 °C and strain rate range of 0.001–1 s−1. It was found that the nucleation mechanisms of discontinuous DRX and continuous DRX (CDRX) occurred simultaneously during hot deformation, and twinning can play an important role in improving the process of DRX. There are three stages in the process of CDRX, i.e., the accumulation and rearrangement of dislocations, the formation of subgrain boundary, and the conversion to high angle grain boundaries (HAGBs) from subgrain boundary. Moreover, the effect of CDRX grows weaker with increasing deformation temperature and decreasing strain rate. Additionally, both the volume fraction of DRX grains and the DRX grain size were closely related to the deformation temperature and strain rate, and a power exponent relationship between the DRX grain size and Z parameter was obtained. Based on the experimental data, the kinetic equations were also developed to evaluate the volume fraction of DRX grains during hot deformation in the alloy.

The thermal conductivities of epoxy composites of mixtures of graphite and graphene in varying ratios were measured. Thermal characterization results showed unexpectedly high conductivities at a certain ratio filler ratio. This phenomenon was exhibited by samples with three different overall filler concentrations (graphene + graphite) of 7, 14, and 35 wt%. The highest thermal conductivity of 42.4 ± 4.8 W/m K (nearly 250 times the thermal conductivity of pristine epoxy) was seen for a sample with 30 wt% graphite and 5 wt% graphene when characterized using the dual-mode heat flow meter technique. This significant improvement in thermal conductivity can be attributed to the lowering of overall thermal interface resistance due to small amounts of nanofillers (graphene) improving the thermal contact between the primary microfillers (graphite). The synergistic effect of this hybrid filler system is lost at higher loadings of the graphene relative to graphite. Graphite and graphene mixed in the ratio of 6:1 yielded the highest thermal conductivities at three different filler loadings.

(CrTaTiVZr)Nx coatings were deposited via reactive radio frequency magnetron sputtering. The effects of N2 flow at 0–8 SCCM on the chemical composition, microstructure, and mechanical properties of the films were investigated. The coatings deposited at a N2 flow of ≤2 SCCM showed a featureless structure with an amorphous phase. When the N2 flow was at 4 SCCM, two distinct layers were observed, namely, the bottom layer (close to the substrate) with an amorphous structure and the top layer with a fibrous structure and face-centered cubic phase. When the N2 flow was further increased, the structure was converted from fibers to columns with larger grains. Accordingly, the maximum hardness value of 36.4 GPa was achieved at a N2 flow of 4 SCCM, thereby indicating that (CrTaTiVZr)Nx coatings may be suitable as hard protective coatings.

This work is an overview of the physical approaches required for characterizing and understanding the long-term evolution of ceramics under irradiation. Because this subject is complex and has many ramifications, we have chosen to address the problem by looking at the behavior of a number of key ceramics. In the first part of this work, we present the physical mechanisms responsible for the production of primary defects, pointing out the main differences between metals, semiconductors, and insulators. In part two, we attempt to show how devoted experimental techniques can combine with transmission electron microscopy and x-ray techniques to provide a clearer picture of the long-term evolution of the microstructure of ceramics under irradiation. The last part of this work is devoted to discussing different approaches to explain and describe the long-term behavior of irradiated ceramics.

Development of new materials for current and advanced reactor concepts is hampered by long lead times and high cost of reactor irradiations coupled with the paucity of test reactors. Ion irradiation offers many advantages for emulating the microstructures and properties of materials irradiated in reactors but also poses many challenges. Nevertheless, there is a growing body of evidence, primarily for light ion (proton) irradiation showing that many, if not all of the features of the irradiated microstructure and properties, can be successfully emulated by careful selection of irradiation parameters based on differences in the damage processes between ion and neutron irradiation. While much less has been done to benchmark heavy- or self-ion irradiation, recent work shows that under certain conditions, the complete suite of features of the irradiated microstructure can be emulated. This study summarizes the contributions of ion irradiation to our understanding of irradiation effects, the options for emulating radiation effects in reactors, and experience with both proton irradiation and heavy ion irradiation.

Investigations of the structural modifications induced in amorphous silica by ion irradiations in a wide energy range from ∼1 MeV to ∼1 GeV are reviewed. Several characterization methods such as infrared spectroscopy, chemical etching, dimensional measurements, and small-angle x-ray scattering have been used to measure the damage induced by individual ions and to analyze its evolution as a function of the energy released by the irradiating species. The comparison of the obtained results shows that high-energy ions lead to the formation along the ion trajectories of damaged zones (called ion tracks) above an electronic energy loss threshold depending on the ion specific energy. This threshold can be as low as ∼1.4 keV/nm for ion beams of 0.2 MeV/u and increases to ∼2.4 keV/nm at ∼5 MeV/u, in agreement with the velocity effect which predicts a narrower radial distribution of the deposited electronic energy with low-velocity ions than with high-velocity ions. Above these threshold values, track radii increase approximately with the square root of the electronic energy loss. In addition, for Au beams between 0.3 and 27 MeV, the generated damage exhibits a U-shaped dependence on the incident ion energy, suggesting a combined effect of the nuclear and electronic energy loss in this energy range. A unified thermal spike model taking into account the contributions of both energy losses allows to reproduce the whole experimental data.

Sn–Ag–Cu solder interconnects were made by solidifying the solder balls in a magnetic field and subsequently tested for their electromigration behavior. The orientation of the tin grains was analyzed by electron backscattered diffraction. It was found that the c-axis of Sn grain tended to rotate away from the direction of the magnetic field during solidification, resulting in an enhanced electromigration resistance for the solder joint when the current was applied along the direction of the magnetic field, as evidenced by a smaller electromigration-induced polarity effect in the growth of the interfacial intermetallic compound. Such a reduced polarity-effect of electromigration is shown to agree well with the anisotropy in the diffusivity of the active diffusion species, Cu, in the tetragonal Sn. The difference of free energy change caused by the anisotropy in the magnetic susceptibility of the tetragonal Sn during solidification is suggested to be the main factor for this phenomenon.

In this study, the interfacial adhesion of Cu and TiN on an annealed borophosphosilicate glass (BPSG) in a multilayer material stack was investigated. The two material systems, Cu/BPSG and TiN/BPSG, are representatives for weak and strong interfaces, respectively. A weak and a strong interface was chosen to identify possible differences in the fracture path selection for the multilayer material systems. To investigate this, in situ 4-point-bending experiments were performed under an optical microscope and in a scanning electron microscope. Complementary ex situ 4-point-bending experiments were carried out on the identical material systems. These tests revealed that for the two analyzed systems there is a large discrepancy in the success rate of failure along the interface of interest, which is a prerequisite for determining the corresponding interface energy release rate. This phenomenon can be understood by using theoretical findings of earlier studies reported in the literature, which are in agreement with the experimental outcome of the in situ 4-point-bending measurements presented here.

The onset of a diffusive phase transformation in thin film Zn0.70Mg0.29Ga0.01O deposited on c-oriented sapphire (α-Al2O3) was explored using dynamic heating experiments in a laser pulsed atom probe tomography (APT) instrument and correlated with transmission electron microscopy (TEM). Specimens were laser irradiated using 100–1000 pJ pulse energies with initial temperatures between 50 and 300 K for up to 8.64 × 1010 pulses. Using a finite element model, it was possible to estimate the temperatures reached by the specimen during laser pulsing, which were calculated to be 300 K to above 1000 K. Due to the small sample volume, quench rates were estimated to be 1013 K/s, allowing for nanosecond temporal resolution during the in situ heating experiments. The formation of Mg-spinel (MgAl2O4) at the transparent conductive oxide/α-Al2O3 substrate interface was observed using electron diffraction and confirmed by atom probe analysis. Subnanometer spatial resolution in the atom probe data reconstructions allowed for near atomic level diffusion to be observed. This work demonstrates the feasibility of conducting these experiments in situ using a combined TEM and APT instrument.

The flow behavior of forged commercial purity (CP) titanium powder compact was studied by developing a processing map. CP titanium powder was sintered to 94% relative density, then hot compressed in a Gleeble thermal–mechanical simulator at strain rates ranging from 0.001 to 10 s−1 and deformation temperatures ranging from 600 to 800 °C. The hot forging process improved the densification to 98–99.9% and reduced the grain size from 93 to 10 µm by the occurrence of dynamic recrystallization. The fully dynamic recrystallization region is in the range of deformation temperature of 750–800 °C and strain rate of 0.001–0.01 s−1, with a power dissipation efficiency higher than 40%, determined by constructing a processing map and analyzing the volume fraction of dynamic recrystallization. This research provides a guide for powder compact forging of power metallurgy titanium by providing the hot compression parameters, which can lead to an improved microstructure and densification.