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2017-01-26
Precision Pointing of Antennas in Space Using Arrays of Shape Memory Alloy Based Linear Actuators
Space systems such as communication satellites, earth observation satellites and space telescopes require precise pointing to observe fixed targets over prolonged time. These systems typically use reaction-wheels to slew the spacecraft and gimballing systems containing motors to achieve precise pointing. Motor based ac...
1701.07561v1
2017-03-04
Tuning the magnetic properties of Fe50-xMnxPt50 thin films
The magnetic and structural properties of highly ordered (S ~ 0.82) epitaxial Fe50-xMnxPt50 thin films were investigated. We report the change in the magnetic properties of Mn doped FePt epitaxial thin films. This study differs from the earlier experimental studies on Mn doped FePt based alloys. Ordered L10 Fe50-xMnxPt...
1703.01510v1
2017-03-18
The Effect of Temperature on Cu-K-In-Se Thin Films
Films of Cu-K-In-Se were co-evaporated at varied K/(K+Cu) compositions and substrate temperatures (with constant (K+Cu)/In ~ 0.85). Increased Na composition on the substrate's surface and decreased growth temperature were both found to favor Cu1-xKxInSe2 (CKIS) alloy formation, relative to mixed-phase CuInSe2 + KInSe2 ...
1703.06366v1
2017-07-25
Thermodynamic and kinetic modeling of Mn-Ni-Si precipitates in low-Cu reactor pressure vessel steels
Formation of large volume fractions of Mn-Ni-Si precipitates (MNSPs) causes excess irradiation embrittlement of reactor pressure vessel (RPV) steels at high, extended-life fluences. Thus, a new and unique, semi-empirical cluster dynamics model was developed to study the evolution of MNSPs in low- Cu RPV steels. The mod...
1707.08072v1
2017-07-28
Predictive modeling of solidification during laser additive manufacturing of nickel superalloys: Recent developments, future directions
Additive manufacturing (AM) processes produce parts with improved physical, chemical, and mechanical properties compared to conventional manufacturing processes. In AM processes, intricate part geometries are produced from multicomponent alloy powder, in a layer-by-layer fashion with multipass laser melting, solidifica...
1707.09292v4
2017-08-20
Si-based GeSn lasers with wavelength coverage of 2 to 3 μm and operating temperatures up to 180 K
A Si-based monolithic laser is highly desirable for full integration of Si-photonics. Lasing from direct bandgap group-IV GeSn alloy has opened a completely new venue from the traditional III-V integration approach. We demonstrated optically pumped GeSn lasers on Si with broad wavelength coverage from 2 to 3 {\mu}m. Th...
1708.05927v1
2017-08-23
Physical properties of the tetragonal CuMnAs: a first-principles study
Electronic, magnetic, and transport properties of the antiferromagnetic (AFM) CuMnAs alloy with tetragonal structure, promising for the AFM spintronics, are studied from first principles using the Vienna ab-initio simulation package. We investigate the site-occupation of sublattices and the lattice parameters of three ...
1708.06916v1
2017-08-25
Ab initio Modelling of the Early Stages of Precipitation in Al-6000 Alloys
Age hardening induced by the formation of (semi)-coherent precipitate phases is crucial for the processing and final properties of the widely used Al-6000 alloys. Early stages of precipitation are particularly important from the fundamental and technological side, but are still far from being fully understood. Here, an...
1708.07908v1
2017-08-29
Mapping the band structure of GeSbTe phase change alloys around the Fermi level
Phase change alloys are used for non-volatile random access memories exploiting the conductivity contrast between amorphous and metastable, crystalline phase. However, this contrast has never been directly related to the electronic band structure. Here, we employ photoelectron spectroscopy to map the relevant bands for...
1708.08787v2
2017-09-14
Increased stability of CuZrAl metallic glasses prepared by physical vapor deposition
We carried out molecular dynamics simulations (MD) using realistic empirical potentials for the vapor deposition (VD) of CuZrAl glasses. VD glasses have higher densities and lower potential and inherent structure energies than the melt-quenched glasses for the same alloys. The optimal substrate temperature for the depo...
1709.04797v1
2017-09-15
Tailoring Semiconductor Lateral Multi-junctions for Giant Photoconductivity Enhancement
Semiconductor heterostructures have played a critical role as the enabler for new science and technology. The emergence of transition metal dichalcogenides (TMDs) as atomically thin semiconductors has opened new frontiers in semiconductor heterostructures either by stacking different TMDs to form vertical heterojunctio...
1709.05410v1
2017-09-18
Magnetic field driven enhanced ferroelectric switching in self-grown ferroelectric-ferromagnetic composite in the BiFeO3-BaTiO3 multiferroic alloy system
Over the years attempts have been made to compensate for the inherent weaknesses in the bulk state of the multiferroic BiFeO3, such as high leakage current and the absence of ferromagnetic correlation, and exploit its magnetoelectric potential by forming solid solutions with other perovskites. Studies in the recent few...
1709.05898v1
2017-10-31
Applied Machine Learning to Predict Stress Hotspots I: Face Centered Cubic Materials
We investigate the formation of stress hotspots in polycrystalline materials under uniaxial tensile deformation by integrating full field crystal plasticity based deformation models and machine learning techniques to gain data driven insights about microstructural properties. Synthetic 3D microstructures are created re...
1711.00118v4
2017-11-16
Strain gradient plasticity-based modeling of hydrogen environment assisted cracking
Finite element analysis of stress about a blunt crack tip, emphasizing finite strain and phenomenological and mechanism-based strain gradient plasticity (SGP) formulations, is integrated with electrochemical assessment of occluded-crack tip hydrogen (H) solubility and two H-decohesion models to predict hydrogen environ...
1711.06179v1
2017-11-22
Interband absorption edge in topological insulators Bi$_2$(Te$_{1-x}$Se$_x$)$_3$
We have investigated the optical properties of thin films of topological insulators Bi$_{2}$Te$_{3}$, Bi$_{2}$Se$_{3}$ and their alloys Bi$_2$(Te$_{1-x}$Se$_x$)$_3$ on BaF$_{2}$ substrates by a combination of infrared ellipsometry and reflectivity in the energy range from 0.06 to 6.5 eV. For the onset of interband abso...
1711.08177v1
2017-12-05
Influence of deformation and annealing twinning on the microstructure and texture evolution of face-centered cubic high-entropy alloys
The influence of the physical mechanisms activated during deformation and annealing on the microstructure and texture evolution as well as on the mechanical properties in the equiatomic CoCrFeMnNi high-entropy alloy (HEA) were investigated. A combination of cold rolling and annealing was used to investigate the HEA in ...
1712.01627v1
2017-12-04
Effect of FePd alloy composition on the dynamics of artificial spin ice
Artificial spin ices (ASI) are arrays of single domain nano-magnetic islands, arranged in geometries that give rise to frustrated magnetostatic interactions. It is possible to reach their ground state via thermal annealing. We have made square ASI using different FePd alloys to vary the magnetization via co-sputtering....
1712.02404v1
2017-11-21
Nanofeatures Induced by Severe Shot Peening (SSP) on Magnesium Alloy AZ31
Considering the sensitivity of both fatigue strength and corrosion rate to the surface characteristics, apposite surface treatments could address the related challenges for biodegradable magnesium-based materials. Herein, we treated the surface of a biocompatible magnesium alloy by a low cost and versatile severe plast...
1712.02834v1
2018-01-08
Interstitial-mediated dislocation climb and the weakening of particle-reinforced alloys under irradiation
Dislocations can climb out of their glide plane by absorbing (or emitting) point defects (vacancies and self-interstitial atoms (SIAs)). In contrast with conservative glide motion, climb relies on the point defects' thermal diffusion and hence operates on much longer timescales, leading to some forms of creep. Whilst e...
1801.02535v1
2018-05-25
Lattice relaxations in disordered Fe-based materials in the paramagnetic state from first principles
In this work we propose a method for the structural relaxation of magnetic materials in the paramagnetic regime, in an adiabatic fast-magnetism approximation within the disordered local moment (DLM) picture in the framework of density functional theory (DFT). The method is straight forward to implement using any $ab$ $...
1805.10110v1
2018-05-30
The evolution of precipitate crystal structures in an Al-Mg-Si(-Cu) alloy studied by a combined HAADF-STEM and SPED approach
This work presents a detailed investigation into the effect of a low Cu addition (0.01 at.%) on precipitation in an Al-0.80Mg-0.85Si alloy during ageing. The precipitate crystal structures were assessed by scanning transmission electron microscopy combined with a novel scanning precession electron diffraction approach,...
1805.11910v1
2018-05-30
Strong spin-Hall and Nernst effects in a p-band semimetal
Since spin currents can be generated, detected, and manipulated via the spin Hall effect (SHE), the design of strong SHE materials has become a focus in the field of spintronics. Because of the recent experimental progress also the spin Nernst effect (SNE), the thermoelectrical counterpart of the SHE, has attracted muc...
1805.12049v1
2018-06-20
Atomic level structure of Ge-Sb-S glasses: chemical short range order and long Sb-S bonds
The structure of Ge$_{20}$Sb$_{10}$S$_{70}$, Ge$_{23}$Sb$_{12}$S$_{65}$ and Ge$_{26}$Sb$_{13}$S$_{61}$ glasses was investigated by neutron diffraction (ND), X-ray diffraction (XRD), extended X-ray absorption fine structure (EXAFS) measurements at the Ge and Sb K-edges as well as Raman scattering. For each composition, ...
1806.07852v1
2018-06-27
Accelerating high-throughput searches for new alloys with active learning of interatomic potentials
We propose an approach to materials prediction that uses a machine-learning interatomic potential to approximate quantum-mechanical energies and an active learning algorithm for the automatic selection of an optimal training dataset. Our approach significantly reduces the amount of DFT calculations needed, resorting to...
1806.10567v1
2018-09-01
Nucleation instability in super-cooled Cu-Zr-Al glass-forming liquids
Special role in computer simulations of supercooled liquid and glasses is played by few general models representing certain classes of real glass-forming systems. Recently, it was shown that one of the most widely used model glassformers -- Kob-Andersen binary Lennard-Jones mixture -- crystalizes in quite lengthy molec...
1809.00198v1
2018-09-10
Diffusion of Mn in gallium nitride: Experiment and modelling
The control over the structural homogeneity is of paramount importance for ternary nitride compounds - the second most important semiconducting material-class after Si, due to its unrivalled applicability in optoelectronics, and high power/high frequency electronics. Therefore it is timely to investigate possible mecha...
1809.03247v1
2018-08-29
Helium-Implantation-Induced Lattice Strains and Defects in Tungsten probed by X-ray Micro-diffraction
Tungsten is the main candidate material for plasma-facing armour components in future fusion reactors. Bombardment with energetic fusion neutrons causes collision cascade damage and defect formation. Interaction of defects with helium, produced by transmutation and injected from the plasma, modifies defect retention an...
1811.05412v2
2019-11-06
A Domain-Specific Language for Verifying Software Requirement Constraints
Software requirement analysis can certainly benefit from prevention and early detection of failures, in particular by some kind of automatic analysis. Formal methods offer means to represent and analyze requirements with rigorous tools, avoiding ambiguities and allowing automatic verification of requirement consistency...
1911.02679v1
2019-11-11
Mechanical properties of VMoNO as a function of oxygen concentration: toward development of hard and tough refractory oxynitrides
Improved toughness is a central goal in the development of wear-resistant refractory ceramic coatings. Extensive theoretical and experimental research has revealed that NaCl structure VMoN alloys exhibit surprisingly high ductility combined with high hardness and toughness. However, during operation, protective coating...
1911.04165v1
2019-11-13
Enhancement of Photovoltaic Current Generation through Dark States in Donor-Acceptor Pairs of Tungsten-based Transition Metal Di-Chalcogenides (TMDCs)
As several photovoltaic materials experimentally approach the Shockley-Queisser limit, there has been a growing interest in unconventional materials and approaches with the potential to cross this efficiency barrier. One such candidate is dark state protection induced by the dipole-dipole interaction between molecular ...
1911.05711v1
2019-11-21
Tuning martensitic transformations via coherent second phases in nanolaminates using free energy landscape engineering
We explore the possibilities and limitations of using a coherent second phase to engineer the thermo-mechanical properties of a martensitic alloy by modifying the underlying free energy landscape that controls the transformation. We use molecular dynamics simulations of a model atomistic system where the properties of ...
1911.09542v3
2020-01-17
Magnetic, magnetoelastic and corrosion resistant properties of (Fe-Ni) based metallic glasses for structural health monitoring applications
We have performed a study of the magnetic, magnetoelastic, and corrosion resistance properties of seven different composition magnetoelastic-resonant platforms. For some applications, such as structural health monitoring, these materials must have not only good magnetomechanical properties, but also a high corrosion re...
2001.06283v1
2021-07-02
Atomic Pathways of Solute Segregation in the Vicinity of Nanoscale Defects
This work unravels the atomic details of the interaction of solute atoms with nanoscale crystalline defects. The complexity of this phenomenon is elucidated through detailed atom probe tomographic investigations on epitaxially-strained, compositionally metastable, semiconductor alloys. Subtle variations are uncovered i...
2107.00800v1
2021-07-14
Halide mixing inhibits exciton transport in two-dimensional perovskites despite phase purity
Metal-halide perovskites are a versatile material platform for light-harvesting and light-emitting applications as their variable chemical composition allows the optoelectronic properties to be tailored to specific applications. Halide mixing is one of the most powerful techniques to tune the optical bandgap of metal-h...
2107.06560v1
2021-07-23
Intermixing Induced Anisotropy Variations in CoB-based Chiral Multilayer Films
We examine the atomic intermixing phenomenon in three distinct amorphous CoB-based multilayer thin film platforms - Pt/CoB/Ir, Ir/CoB/Pt and Pt/CoB/MgO - which are shown to stabilise room-temperature chiral magnetic textures. Intermixing occurs predominantly between adjacent metallic layers. Notably, it is stack-order ...
2107.11034v1
2021-07-28
First principles prediction of the Al-Li phase diagram
The phase diagram of the Al-Li system was determined by means of first principles calculations in combination with the cluster expansion formalism and statistical mechanics. The ground state phases were determined from first principles calculations of fcc and bcc configurations in the whole compositional range while th...
2107.13645v1
2017-04-08
Thermal memory fading by heating to a lower temperature: experimental data on polycrystalline NiFeGa ribbons and 2D statistical model predictions
Shape memory alloys are known to memorise one -or several- temperatures at which the martensite-austenite transformation was stopped before completion in the past, the memory manifesting as specific dips in subsequent calorimetric scans. Previous studies have shown that this memory can be erased by heating to higher te...
1704.02443v1
2017-04-18
Extruded Mg based hybrid composite alloys studied by longitudinal impression creep
The creep behaviour of a creep-resistant AE42 magnesium alloy reinforced with Saffil short fibres and SiC particulates in various combinations has been examined in the longitudinal direction, i.e., the plane containing random fibre orientation was parallel to the loading direction, in the temperature range of 175-300 C...
1704.06563v2
2018-07-16
Nematicity of correlated systems driven by anisotropic chemical phase separation
The origin of nematicity, i.e., in-plane rotational symmetry breaking, and in particular the relative role played by spontaneous unidirectional ordering of spin, orbital, or charge degrees of freedom, is a challenging issue of magnetism, unconventional superconductivity, and quantum Hall effect systems, discussed in th...
1807.05966v3
2018-07-29
Dynamic control of anapole states with phase-change alloys
High-index dielectric nanoparticles supporting a distinct series of Mie resonances have enabled a new class of optical antennas with unprecedented functionalities. The great wealth of multipolar responses and their delicate interplay have not only spurred practical developments but also brought new insight into fundame...
1807.11015v1
2018-10-10
A Machine Learning Approach for Increased Throughput of Density Functional Theory Substitutional Alloy Studies
In this study, a machine learning-based technique is developed to reduce the computational cost required to explore large design spaces of substitutional alloys. The first advancement is based on a neural network approach to predict the initial position of ions for both minority and majority ions before ion relaxation....
1810.04687v3
2018-10-25
Exchange dependent ultrafast magnetization dynamics in Fe$_{1-x}$Ni$_{x}$ alloys
Element specific ultrafast demagnetization was studied in Fe$_{1-x}$Ni$_{x}$ alloys, covering the concentration range between $0.1<x<0.9$. For all compositions, we observe a delay in the onset of Ni demagnetization relative to the Fe demagnetization. We find that the delay is correlated to the Curie temperature and hen...
1810.11001v1
2018-10-30
Computational methods for creation materials with required composition and structure
One of the most important and complicated problems in modern industry is to obtaining materials with the required chemical composition, structure and mechanical and physical properties. Solving this problem involves great deal of time and expense, and the results obtained might be far from the optimal solution. The are...
1810.12534v1
2018-10-30
CLEASE: A versatile and user-friendly implementation of Cluster Expansion method
Materials exhibiting a substitutional disorder such as multicomponent alloys and mixed metal oxides/oxyfluorides are of great importance in many scientific and technological sectors. Disordered materials constitute an overwhelmingly large configurational space, which makes it practically impossible to be explored manua...
1810.12816v2
2019-01-03
Calculating spin transport properties from first principles: spin currents
Local charge and spin currents are evaluated from the solutions of fully relativistic quantum mechanical scattering calculations for systems that include temperature-induced lattice and spin disorder as well as intrinsic alloy disorder. This makes it possible to determine material-specific spin transport parameters at ...
1901.00703v1
2019-01-09
Epitaxial phases of high Bi content GaSbBi alloys
GaSbBi alloys have recently emerged as attractive materials for mid-infrared optoelectronics owing to strong band gap reduction enabled by Bi incorporation into the GaSb matrix. The fundamental understanding of the epitaxial process required to demonstrate high quality crystals is in an early-developmental phase. From ...
1901.02687v1
2019-01-28
Strong damping-like spin-orbit torque and tunable Dzyaloshinskii-Moriya interaction generated by low-resistivity Pd$_{1-x}$Pt$_x$ alloys
Despite their great promise for providing a pathway for very efficient and fast manipulation of magnetization at the nanoscale, spin-orbit torque (SOT) operations are currently energy inefficient due to a low damping-like SOT efficiency per unit current bias, and/or the very high resistivity of the spin Hall materials....
1901.09954v1
2019-01-29
Broken time-reversal symmetry in superconducting Pr$_{1-x}$La$_{x}$Pt$_{4}$Ge$_{12}$
The superconducting state of the filled skutterudite alloy series Pr$_{1-x}$La$_{x}$Pt$_{4}$Ge$_{12}$ has been systematically studied by specific heat, zero-field muon spin relaxation ($\mu$SR), and superconducting critical field measurements. An additional inhomogeneous local magnetic field, indicative of broken time-...
1901.10224v1
2019-03-30
Electronic band structure of nitrogen diluted Ga(PAsN): Formation of the intermediate band, direct and indirect optical transitions, localization of states
The electronic band structure of Ga(PAsN) with a few percent of nitrogen is calculated in the whole composition of Ga(PAs) host using the state-of-the-art density functional methods including the modified Becke-Johnson functional to correctly reproduce the band gap, and band unfolding to reveal the character of the ban...
1904.00159v1
2019-04-10
Phonon localization in binary alloys with diagonal and off-diagonal disorder: A cluster Green's function approach
We report the development and application of a new method for carrying out computational investigations of the effects of mass and force-constant (FC) disorder on phonon spectra. The method is based on the recently developed typical medium dynamical cluster approach (TMDCA), which is a Green's function approach. Excell...
1904.05324v2
2019-04-19
Crystal plasticity analysis of deformation anisotropy of lamellar TiAl alloy: 3D microstructure-based modelling and in-situ micro-compression
Detailed microstructure characterisation and in-situ micropillar compression were coupled with crystal plasticity-based finite element modelling (CP-FEM) to study the micro-mechanisms of plastic anisotropy in lamellar TiAl alloys. The consideration of microstructure in both simulation and in-situ experiments enables in...
1904.09206v1
2019-04-21
Flux effects in precipitation under irradiation - Simulation of Fe-Cr alloys
Radiation-enhanced precipitation of Cr-rich {\alpha}' in irradiated Fe-Cr alloys, which results in hardening and embrittlement, depends on the irradiating particle and the displacement per atom (dpa) rate. Here, we utilize a Cahn-Hilliard phase-field based approach, that includes simple models for nucleation, irradiati...
1904.09682v1
2019-07-04
Splitting up entropy into vibrational and configurational contributions in bulk metallic glasses: A thermodynamic approach
We applied an efficient methodology to separate vibrational and configurational entropies in bulk metallic glasses by means of molecular dynamics simulation based on a combination of non-equilibrium adiabatic switching and reversible scaling methods. This approach involves calculating the vibrational free energy using ...
1907.02611v5
2019-07-15
Current-driven domain wall dynamics in ferrimagnets: micromagnetic approach and collective coordinates model
Theoretical studies dealing with current-driven domain wall dynamics in ferrimagnetic alloys and, by extension, other antiferromagnetically coupled systems as some multilayers, are here presented. The analysis has been made by means of micromagnetic simulations that consider these systems as constituted by two subsyste...
1907.06431v1
2019-07-15
Nature of the magnetic moment of cobalt in ordered FeCo alloy
The magnets are typically classified into Stoner and Heisenberg type, depending on the itinerant or localized nature of the constituent magnetic moments. In this work, we investigate theoretically the behaviour of the magnetic moments of iron and cobalt in their B2-ordered alloy. The results based on local spin density...
1907.06613v5
2019-07-16
Robust surface states and coherence phenomena in magnetically alloyed SmB6
Samarium hexaboride is a candidate for the topological Kondo insulator state, in which Kondo coherence is predicted to give rise to an insulating gap spanned by topological surface states. Here we investigate the surface and bulk electronic properties of magnetically alloyed Sm1-xMxB6 (M=Ce, Eu), using angle-resolved p...
1907.07074v3
2019-07-23
Plate-like precipitate effects on plasticity of Al-Cu alloys at micrometer to submicrometer scales
The continuous miniaturization of modern electromechanical systems calls for a comprehensive understanding of the mechanical properties of metallic materials specific to micrometer and sub-micrometer scales. At these scales, the nature of dislocation-mediated plasticity changes radically: sub-micrometer metallic sample...
1907.09818v2
2019-07-24
Thermoelectric Properties of BiSbTe Alloy Nanofilms Produced by DC Sputtering: Experiments and Modeling
Thermoelectricity refers to the conversion of thermal energy into electrical energy and vice-versa, which relies on three main effects: Seebeck, Peltier and Thomson, all of which are manifestations of heat and electricity flow. In this work we investigate the deposition of nanometric films and the effect of a thermal t...
1907.10730v1
2019-07-26
Plate-like precipitate effects on plasticity of Al-Cu micro-pillar: {100}-interfacial slip
In this paper, we study the effects of $\theta ^\prime$-Al$_2$Cu plate-like precipitates on the plasticity of Al-Cu micro-pillars, with a sample size allowing the precipitates to cross the entire micro-pillar. {100}-slip traces are identified for the first time in Al and Al alloys at room temperature. We investigate th...
1907.11390v1
2019-10-18
Pressure effects on the electronic structure and superconductivity of (TaNb)$_{0.67}$(HfZrTi)$_{0.33}$ high entropy alloy
Effects of pressure on the electronic structure, electron-phonon interaction, and superconductivity of the high entropy alloy (TaNb)$_{0.67}$(HfZrTi)$_{0.33}$ are studied in the pressure range 0 - 100 GPa. The electronic structure is calculated using the Korringa-Kohn-Rostoker method with the coherent potential approxi...
1910.08312v1
2019-10-24
Segregation and Preferential Sputtering of Cr in WCrY Smart Alloy
The temperature driven segregation of Cr to the surface of the tungsten-based WCrY alloy is analysed with low energy ion scattering of He+ ions with an energy of 1 keV in the temperature range from room temperature to 1000 K. Due to the high surface sensitivity, these measurements probe only the composition of the oute...
1910.11234v2
2019-10-29
Direct Optical-Structure Correlation in Atomically Thin Dichalcogenides and Heterostructures
Atomically thin transition metal dichalcogenides (TMDs) have distinct opto-electronic properties including enhanced luminescence and high on-off current ratios, which can be further modulated by making more complex TMD heterostructures. However, resolution limits of conventional optical methods do not allow for direct ...
1910.13387v1
2018-08-14
Artificial Intelligence for High-Throughput Discovery of Topological Insulators: the Example of Alloyed Tetradymites
Significant advances have been made in predicting new topological materials using high-throughput empirical descriptors or symmetry-based indicators. To date, these approaches have been applied to materials in existing databases, and are severely limited to systems with well-defined symmetries, leaving a much larger ma...
1808.04733v4
2018-08-16
A disclosure of the role of frequency on the plasma electrolytic oxidation of AZ31 magnesium alloy in aluminate-tungstate electrolyte
Plasma electrolytic oxidation (PEO) was carried out to form black ceramic coatings on AZ31 magnesium alloy in aluminate-tungstate electrolyte. Influences of current frequency (such as 100, 1000 and 2000 Hz) on properties of the PEO coatings have been explored. It was found that increment of frequency led to coatings wi...
1808.06587v1
2018-08-10
Parametric Analysis of a Phenomenological Constitutive Model for Thermally Induced Phase Transformation in Ni-Ti Shape Memory Alloys
In this work, a thermo-mechanical model that predicts the actuation response of shape memory alloys is probabilistically calibrated against three experimental data sets simultaneously. Before calibration, a design of experiments (DOE) has been performed in order to identify the parameters most influential on the actuat...
1808.07377v1
2018-12-11
Phase-field analysis of quenching and partitioning in a polycrystalline Fe-C system under constrained-carbon equilibrium condition
Mechanical properties of steels are significantly enhanced by retained austenite. Particularly, it has been shown that a recently developed heat-treatment technique called Quenching and Partitioning (Q\&P) stabilises austenite effectively. In the present work, the phase-field approach is adopted to simulate the phase t...
1812.04306v1
2018-12-13
A Finite Strain Constitutive Model for Martensitic Transformation in Shape Memory Alloys Based on Logarithmic Strain
Shape Memory Alloys (SMAs) are materials with the ability to recover apparently permanent deformation under specific thermomechanical loading. The majority of constitutive models for SMAs are developed based on the infinitesimal strain theory. However, such assumption may not be proper in the presence of geometric disc...
1812.05696v1
2018-12-13
A Three-dimensional Constitutive Model for Polycrystalline Shape Memory Alloys Under Large Strains Combined With Large Rotations
Shape Memory Alloys (SMAs) has been widely aware of working as actuators for active/smart morphing structures in the engineering industry. Because of the high actuation energy density of SMAs, compared to other active materials, structures integrated with SMA-based actuators has high advantage in terms of trade-offs be...
1812.05700v2
2018-12-17
Excitonic Complexes and Emerging Interlayer Electron-Phonon Coupling in BN Encapsulated Monolayer Semiconductor Alloy: WS0.6Se1.4
Monolayer transition metal dichalcogenides (TMDs) possess superior optical properties, including the valley degree of freedom that can be accessed through the excitation light of certain helicity. While WS2 and WSe2 are known for their excellent valley polarization due to the strong spin-orbit coupling, the optical ban...
1812.06758v1
2018-12-13
A Three-Dimensional Constitutive Modeling for Shape Memory Alloys Considering Two-Way Shape Memory Effect and Transformation-Induced Plasticity
Shape memory alloys (SMAs) have been intensively investigated as actuators for the past several decades. Due to their high actuation energy density compared to other active materials, their current and potential applications in engineering fields are expanding rapidly. Prior to being used as actuators, SMAs are usually...
1812.10466v1
2019-02-13
Strain Controlling Catalytic Efficiency of Water Oxidation for Ni1-xFexOOH alloy
A catalyst surface may be exposed to strain due to application of load or interfacing with a substrate with large lattice mismatch. In order to test the effect of strain on catalytic efficiency, we use Density Functional Theory +U (DFT+U) to model water oxidation on expanded and contracted surfaces of the Ni1-xFexOOH a...
1902.04788v1
2019-02-25
Atomistic Simulations of Basal Dislocations Interacting with Mg$_{17}$Al$_{12}$ Precipitates in Mg
The mechanical properties of Mg-Al alloys are greatly influenced by the complex intermetallic phase Mg$_{17}$Al$_{12}$, which is the most dominant precipitate found in this alloy system. The interaction of basal edge and 30$^\text{o}$ dislocations with Mg$_{17}$Al$_{12}$ precipitates is studied by molecular dynamics an...
1902.09446v2
2019-06-06
Novel Mechanocaloric Materials for Solid-State Cooling Applications
Solid-state cooling is an environmentally friendly and highly scalable technology that may solve most of the problems associated with current refrigerant methods. Solid-state cooling consists of applying external fields on caloric materials, which react thermally as a result of induced phase transformations. From an en...
1906.02363v1
2019-06-17
Sub-single exciton optical gain threshold in colloidal semiconductor quantum wells with gradient alloy shelling
Colloidal semiconductor quantum wells have emerged as a promising material platform for use in solution-processable light-generation including colloidal lasers. However, application relying on their optical gain suffer from a fundamental complication due to multi-excitonic nature of light amplification in common II-VI ...
1906.06913v1
2020-04-09
Efficient determination of solid-state phase equilibrium with the Mutli-Cell Monte Carlo method
Building on our previously introduced Multi-cell Monte Carlo (MC)^2 method for modeling phase coexistence, this paper provides important improvements for efficient determination of phase equilibria in solids. The (MC)^2 method uses multiple cells, representing possible phases. Mass transfer between cells is modeled vir...
2004.04673v2
2020-05-15
Doping-induced spin Hall ratio enhancement in A15-phase, Ta-doped Beta-W thin films
As spintronic devices become more and more prevalent, the desire to find Pt free materials with large spin Hall effects is increasing. Previously it was shown that Beta W, the metastable A15 structured variant of pure W, has charge-spin conversion efficiencies on par with Pt, and it was predicted that Beta W(Ta) alloys...
2005.07681v2
2020-05-29
Single-Atom Alloy Catalysts Designed by First-Principles Calculations and Artificial Intelligence
Single-atom metal alloy catalysts (SAACs) have recently become a very active new frontier in catalysis research. The simultaneous optimization of both facile dissociation of reactants and a balanced strength of intermediates' binding make them highly efficient and selective for many industrially important reactions. Ho...
2005.14422v1
2020-08-03
Solute hydrogen and deuterium observed at the near atomic scale in high-strength steel
Observing solute hydrogen (H) in matter is a formidable challenge, yet, enabling quantitative imaging of H at the atomic-scale is critical to understand its deleterious influence on the mechanical strength of many metallic alloys that has resulted in many catastrophic failures of engineering parts and structures. Here,...
2008.00684v1
2020-08-07
Monolithic integration of InP on Si by molten alloy driven selective area epitaxial growth
We report a new approach for monolithic integration of III-V materials into silicon, based on selective area growth and driven by a molten alloy in metal-organic vapor epitaxy. Our method includes elements of both selective area and droplet-mediated growths and combines the advantages of the two techniques. Using this ...
2008.03054v1
2020-08-12
Metastable skyrmion lattices governed by magnetic disorder and anisotropy in $β$-Mn-type chiral magnets
Magnetic skyrmions are vortex-like topological spin textures often observed in structurally chiral magnets with Dzyaloshinskii-Moriya interaction. Among them, Co-Zn-Mn alloys with a $\beta$-Mn-type chiral structure host skyrmions above room temperature. In this system, it has recently been found that skyrmions persist ...
2008.05075v1
2020-08-20
Ensemble learning reveals dissimilarity between rare-earth transition metal binary alloys with respect to the Curie temperature
We propose a data-driven method to extract dissimilarity between materials, with respect to a given target physical property. The technique is based on an ensemble method with Kernel ridge regression as the predicting model; multiple random subset sampling of the materials is done to generate prediction models and the ...
2008.08818v1
2020-08-28
Composition dependence of tracer diffusion coefficients in Fe-Ga alloys: a case study by a tracer-interdiffusion couple method
The problem of estimation of the tracer diffusion coefficients is solved by utilizing a novel tracer-interdiffusion couple technique even in the absence suitable radioisotope of one of the components and absence of reliable thermodynamic parameters. This is demonstrated by generating reliable and reproducible mobility ...
2008.12533v1
2021-02-28
Accelerated design of linear-superelastic Ti-Nb nanocomposite alloys with ultralow modulus via high-throughput phase-field simulations and machine learning
The controlled design of martensitic transformation (MT) to achieve specific properties is crucial for the innovative application of shape memory alloys (SMAs) in advanced technologies. Herein, we explore and design the MT behaviors and the mechanical properties of Ti-Nb nanocomposites by combining high-throughput phas...
2103.00513v4
2021-03-02
Reflections on the spatial performance of atom probe tomography in the analysis of atomic neighbourhoods
Atom probe tomography is often introduced as providing "atomic-scale" mapping of the composition of materials and as such is often exploited to analyse atomic neighbourhoods within a material. Yet quantifying the actual spatial performance of the technique in a general case remains challenging, as they depend on the ma...
2103.01665v2
2021-03-04
Photo-emission signatures of coherence breakdown in Kondo alloys: dynamical mean-field theory approach
We study the Kondo alloy model on a square lattice using dynamical mean-field theory (DMFT) for Kondo substitution and disorder effects, together with static mean-field approximations. We computed and analyzed photoemission properties as a function of electronic filling $n_c$, Kondo impurity concentration $x$, and stre...
2103.03182v2
2021-03-05
Ferromagnetic Composite Self-Arrangement in Iron-Implanted Epitaxial Palladium Thin Films
We report on the formation of the dilute $Pd_{1-x}Fe_x$ compositions with tunable magnetic properties under an ion-beam implantation of epitaxial Pd thin films. Binary $Pd_{1-x}Fe_x$ alloys with a mean iron content $x$ of $0.025$, $0.035$ or $0.075$ were obtained by the implantation of $40 keV$ $Fe^+$ ions into the pal...
2103.03562v1
2021-03-05
A Hybrid Dynamical Modeling Framework for Shape Memory Alloy Wire Actuated Structures
In this paper, a hybrid model for single-crystal Shape Memory Alloy (SMA) wire actuators is presented. The result is based on a mathematical reformulation of the M\"uller-Achenbach-Seelecke (MAS) model, which provides an accurate and interconnection-oriented description of the SMA hysteretic response. The strong nonlin...
2103.03586v1
2021-03-09
Ultrafast demagnetization in a ferrimagnet under electromagnetic field funneling
The quest to improve density, speed and energy efficiency of magnetic memory storage has led to exploration of new ways of optically manipulating magnetism at the ultrafast time scale, in particular in ferrimagnetic alloys. While all-optical magnetization switching is well-established on the femtosecond timescale, late...
2103.05365v1
2021-03-10
The Taming of Plutonium: Pu Metallurgy and the Manhattan Project
We describe the wartime challenges associated with the rapid developments in plutonium chemistry and metallurgy that were necessary to produce the core of the Trinity Device. Beginning with microgram quantities of plutonium metal late in 1943, initial measurements showed a wide and confusing variance in density and oth...
2103.06226v1
2021-03-16
Wegner estimate and localisation for alloy type operators with minimal support assumptions on the single site potential
We prove a Wegner estimate for alloy type models merely assuming that the single site potential is lower bounded by a characteristic function of a thick set, that is a particular set of positive measure. The proof is based on two ingredients: New unique continuation principles or uncertainty relations for linear combin...
2103.09012v3
2021-03-25
Properties of α-Brass Nanoparticles II: Structure and Composition
Nanoparticles have become increasingly interesting for a wide range of applications, because in principle it is possible to tailor their properties by controlling size, shape and composition. One of these applications is heterogeneous catalysis, and a fundamental understanding of the structural details of the nanoparti...
2103.14130v2
2021-03-26
Enhanced Thermoelectric Performance of Polycrystalline Si0.8Ge0.2 Alloys through the Addition of Nanoscale Porosity
Engineering materials to include nanoscale porosity or other nanoscale structures has become a well-established strategy for enhancing the thermoelectric performance of dielectrics. However, the approach is only considered beneficial for materials where the intrinsic phonon mean-free path is much longer than that of th...
2103.14223v2
2021-03-30
Soft X-ray absorption spectroscopy and magnetic circular dichroism under pulsed high magnetic field of Ni-Co-Mn-In metamagnetic shape memory alloy
In this study, X-ray absorption spectroscopy (XAS) experiments for Ni45Co5Mn36.7In13.3 metamagnetic shape memory alloy were performed under high magnetic fields up to 12 T using a pulsed magnet. Field-induced reverse transformation to austenite phase caused considerable changes in the magnetic circular dichroism (MCD) ...
2103.16296v3
2021-03-30
Segregation competition and complexion coexistence within a polycrystalline grain boundary network
Interfacial segregation can stabilize grain structures and even lead to grain boundary complexion transitions. However, understanding of the complexity of such phenomena in polycrystalline materials is limited, as most studies focus on bicrystal geometries. In this work, we investigate interfacial segregation and subse...
2103.16678v2
2022-02-07
Locally Random Alloy Codes with Channel Coding Theorems for Distributed Matrix Multiplication
Matrix multiplication is a fundamental operation in machine learning and is commonly distributed into multiple parallel tasks for large datasets. Stragglers and other failures can severely impact the overall completion time. Recent works in coded computing provide a novel strategy to mitigate stragglers with coded task...
2202.03469v5
2022-03-04
Machine-learning enabled thermodynamic model for the design of new rare-earth compounds
We employ a descriptor based machine-learning approach to assess the effect of chemical alloying on formation-enthalpy of rare-earth intermetallics. Application of machine-learning approaches in rare-earth intermetallic design have been sparse due to limited availability of reliable datasets. In this work, we developed...
2203.02391v1
2022-03-07
Multi-scale Investigation of Chemical Short-Range Order and Dislocation Glide in the MoNbTi and TaNbTi Refractory Multi-Principal Element Alloys
Refractory multi-principal element alloys (RMPEAs) are promising materials for high-temperature structural applications. Here, we investigate the role of chemical short-range ordering (CSRO) on dislocation glide in two model RMPEAs - TaNbTi and MoNbTi - using a multi-scale modeling approach. A highly accurate machine l...
2203.03767v1
2022-03-08
Electronic effects on the radiation damage in high-entropy alloys
High-entropy alloys (HEAs) are exceptional candidates for radiation-resistant materials due to their complex local chemical environment and slow defect migration. Despite commonly overlooked, electronic effects on defects evolution in radiation environments also play a crucial role by dissipating excess energy through ...
2203.03779v2
2022-03-16
Effect of hydrogen gas on magnetic properties of alloys of ferromagnetic metals with Pd and its application in hydrogen gas sensing
The mass-production of fuel-cell vehicles and the eventual transition to the hydrogen economy will require safe, inexpensive and reliable sensors capable of simultaneously detecting low concentrations of leaking hydrogen and measuring broad ranges of hydrogen concentration in storage and energy generating systems. Alth...
2203.08575v1
2016-03-30
Evidence of quantum Griffiths phase in Ni_{1-x}V_x nanoalloys
Metallic Ni$_{1-x}$V$_x$ alloys are known to exhibit a ferromagnetic to paramagnetic disordered quantum phase transition (QPT) at the critical concentration $x_c \sim$ 0.114 in bulk. Such a QPT is accompanied by a quantum Griffiths phase (QGP), the physical observables in which follow non-universal power-law temperatur...
1603.09034v1