A5040444844- Shape Memory Alloy Transformations
- Intermetallics and Advanced Alloy Properties
- Electron and X-Ray Spectroscopy Techniques
- Planetary Science and Exploration
- Microstructure and Mechanical Properties of Steels
- Astro and Planetary Science
- Microstructure and mechanical properties
- Semiconductor materials and devices
- X-ray Spectroscopy and Fluorescence Analysis
- Ferroelectric and Piezoelectric Materials
- Spacecraft and Cryogenic Technologies
- High Entropy Alloys Studies
- Advanced Materials Characterization Techniques
- Magnetic and transport properties of perovskites and related materials
- High-pressure geophysics and materials
- Nuclear Physics and Applications
- Vacuum and Plasma Arcs
- Boron and Carbon Nanomaterials Research
- Titanium Alloys Microstructure and Properties
- Metal and Thin Film Mechanics
- Advanced Measurement and Detection Methods
- Solidification and crystal growth phenomena
- Space Exploration and Technology
- Corrosion Behavior and Inhibition
- Fusion materials and technologies
Jet Propulsion Laboratory
2023-2024
Ruhr University Bochum
2012-2014
Northwestern University
2007-2009
Due to the importance of NiTi as a shape-memory material and uncertainty regarding its atomisitic martensitic transformation path, thorough investigation understand structural stability governing this displacive phase is warranted. We investigate elastic shear stabilities using first-principles calculations with highly precise full-potential linearized augmented plane-wave method. Ambiguities B2, R, B19, $\text{B}1{9}^{\ensuremath{'}}$, proposed B33 structures are resolved, we establish that...
We present the structural evolution mechanism during NiTi martensitic transformation and show origins of this behavior in electronic phononic anomalies. By employing highly precise all-electron density-functional theory calculations, we establish a barrierless path for equiatomic consisting basal shear composed bilayer $⟨100⟩{011}$ stacking faults to B2 phase followed by another which causes relaxation structure's monoclinic angle results $\text{B}1{9}^{\ensuremath{'}}$ phase. This is traced...
<title>Abstract</title> Jupiter’s icy moon Europa is an ocean world which a prime candidate in our search for potential extraterrestrial habitability and life beyond Earth. Europa’s surface hosts many features proposed to originate from brine sources within its shell (Fagents, 2003), may represent the most accessible liquid water bodies Solar System (Lesage et al., 2022). An intriguing possible example asterisk-shaped ‘spider’ at center of Manannán crater, identified by Galileo mission...
Formation of the Ni4Ti3 precipitate has a strong effect on shape memory properties NiTi alloys. In this work, growth is studied using phase-field modelling and density functional theory (DFT) calculations. Using first-principles calculations, composition-dependent stability elastic B2 phase are obtained. Composition-dependent constants incorporated into our model to investigate interplay between stress concentration fields around precipitate. The introduces source diffusion due mechanical...
A coherent transferable tight-binding (TB) parametrization including magnetism has been developed for the Fe-C interaction. We use a downfolding procedure to obtain continuous and bond integrals from density functional theory. TB model is constructed using these parameterized interatomic repulsion based on simple exponentials fit excess energy of interstitial carbon in $\ensuremath{\alpha}$, $\ensuremath{\gamma}$, $\ensuremath{\epsilon}$ iron. An accurate description hierarchy structures can...
We employ a recently developed iron–carbon orthogonal tight-binding model in calculations of carbon iron grain boundaries. use the to evaluate properties near and on Σ5 (3 1 0)[0 0 1] symmetric tilt boundary (GB) iron, show that atom lowers GB energy by 0.29 eV/atom accordance with DFT. Carbon segregation is analyzed, we find an barrier 0.92 eV for segregate carbon-free interface while fully filled disfavored. Local volume (via Voronoi tessellation), magnetic, electronic effects are...
Spin-dependent transport of low-energy electrons $(\ensuremath{\leqslant}500\phantom{\rule{0.3em}{0ex}}\mathrm{eV})$ through metals is studied using Monte Carlo simulations which employ collision kernels constructed from microscopic response functions and spin density states calculated with the functional full-potential linearized augmented plane wave method. Trajectories are simulated as sequences stochastic elastic inelastic scattering events including spin-dependent processes. We apply...
To determine the effect of ternary additions on martensitic behavior NiTi, we apply ab initio calculations using highly precise full-potential linearized augmented plane wave method to Ni-Ti-Pt system.We compare formation energies various stoichiometries and pair energetics between Pt atoms create a number model austenite structures, finding that prefer decorate lattice at third nearest neighbors from one another, establish hierarchy among austenitic phases.We examine structural stability...
We study spin-dependent scattering and transport of low energy electrons (≤ 500 eV) through metals employing a classical theory within which electron trajectories are simulated as sequence stochastic events. Elastic well inelastic processes included in our model simulating the complete secondary cascade. apply to spin-polarization measurements emitted from magnetized Fe after impact unpolarized primary electrons. find good agreement with experimental data.
In the exploration of icy ocean worlds, including Enceladus, Europa, and Titan, absence information related to material properties surface requires that sampling subsystems possess a robust capability interact with broad variety potential terrain scenarios. To aid in development can navigate challenges excavation, sample collection, delivery conditions, we aim reproducibly generate plausible solid simulants range mechanical at scale relevant activities tools testbeds. This paper presents...
Titanium-zirconium-molybdenum (TZM) is often used in telescope and spectrometer detector assemblies as a structure-detector interface due to its thermal expansion compatibility with HgCdTe-based focal plane arrays. This alloy has been several flight missions at NASA Jet Propulsion Laboratory (JPL) including James Webb Space Telescope, Euclid, more recently, Spectro-Photometer for the History of Universe, Epoch Reionization (SPHEREx) Contribution ARIEL Spectroscopy Exoplanets (CASE). On these...
Acktar Advanced Coating's Fractal Black™ is an inorganic vacuum-deposited thermal-optical control coating with well-established absorptivity and emissivity from ultraviolet to thermal infrared ranges. This has been used in the aerospace industry for stray light passive management its low reflectance visible infra-red spectra, large working temperature range, outgassing. Black proven outperform traditional spray coatings complex geometries terms of conformance small radii curvature substrate...