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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Suppression of anti-phase boundary defects in Mn-Al-Ti permanent magnets
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Role of face centered cubic/body centered cubic phase boundary crystallography on void growth
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Interfacial intermixing and anti-phase boundaries in GaP/Si(0 0 1) heterostructures
Epitaxial GaP/Si heterostructures grown by molecular beam epitaxy (MBE) and migration-enhanced epitaxy (MEE) have been studied, primarily using aberration-corrected scanning transmission electron microscopy (AC-STEM). Atomically-resolved structure images, which are sensitive to atomic-column intensity revealed the detailed geometry of antiphase boundaries that were both parallel and also inclined to the growth direction. The polar/non-polar GaP/Si interfaces were neither atomically flat laterally nor abrupt vertically. Measurements of intensity profiles using both bright-field and dark-field AC-STEM images, as well as chemically-sensitive g 002 dark-field imaging, indicated substantial interfacial intermixing, which increased significantly from ~1.3 nm (MEE growth at 440 °C) to ~2.1 nm (MBE growth at 600 °C). The finite interface width will impact theoretical predictions of charge imbalance and strong electric fields across the heterointerface.
Causal Analysis of Parameterized Atomic HAADF-STEM Across a Doped Ferroelectric Phase Boundary
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Crystal structure and actuation mechanisms in morphotropic phase boundary Pb(Zn[subscript 1/3]Nb[sub
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Characterization of Grain Boundary Phase Transformations
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Pattern Formation of Grain Boundary Phases
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Constraining the Platinum Liquid-Vapor Phase Boundary and Critical Point with Fluid Flyer Experiments
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Constraining the platinum liquid-vapor phase boundary and critical point with fluid flyer experiments
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Phase boundary motion and polyphase diffusion in binary metal-interstitial systems.
Polyphase diffusion and interface growth in binary metal interstitial systems via Fick first law, deriving parabolic growth law for interface motion
Crystallization of the glassy grain boundary phase in silicon nitride ceramics
The role was studied of the intergranular glassy phase in silicon nitride as-processed with yttria as a sintering aid. The microstructure, crystallization, and viscosity of the glassy phase were areas studied. Crystallization of the intergranular glassy phase to more refractory crystalline phases should improve the high temperature mechanical properties of the silicon nitride. The addition of a nucleating agent will increase the rate of crystallization. The measurement of the viscosity of the glassy phase will permit the estimation of the high temperature deformation of the silicon nitride.
(abstract) Fundamental Mechanisms of Electrode Kinetics and Alkali Metal Atom Transport at the Alkali Beta'-Alumina/Porous Electrode/Alkali Metal Vapor Three Phase Boundary
The mechanisms of electrode kinetics and mass transport of alkali metal oxidation and alkali metal cation reduction at the solid electrolyte/porous electrode boundary as well as alkali metal transport through porous metal electrodes has important applications in optimizing device performance in alkali metal thermal to electric converter (AMTEC) cells which are high temperature, high current density electrochemical cells. Basic studies of these processes also affords the opportunity to investigate a very basic electrochemical reaction over a wide range of conditions; and a variety of mass transport modes at high temperatures via electrochemical techniques. The temperature range of these investigations covers 700K to 1240K; the alkali metal vapor pressures range from about 10(sup -2) to 10(sup 2) Pa; and electrodes studied have included Mo, W, Mo/Na(sub 2)MoO(sub 4), W/Na(sub 2)WO(sub 4), WPt(sub x), and WRh(sub x) (1.0 < x < 6.0 ) with Na at Na-beta'-alumina, and Mo with K at K-beta'-alumina. Both liquid metal/solid electrolyte/alkali metal vapor and alkali metal vapor/solid electrolyte/vapor cells have been used to characterize the reaction and transport processes. We have previously reported evidence of ionic, free molecular flow, and surface transport of sodium in several types of AMTEC electrodes.
Experimental and computational phase boundary mapping of Co 4 Sn 6 Te 6
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Supercapillary Architecture‐Activated Two‐Phase Boundary Layer Structures for Highly Stable and Efficient Flow Boiling Heat Transfer
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Kinetics of HCP-BCC Phase Transition Boundary in Magnesium at High Pressure
Under high pressures, many crystalline metals undergo solid–solid phase transformations. In order to accurately model the behavior of materials under extreme loading conditions, it is essential to understand the kinetics of phase transition. Using molecular dynamics simulations, this work demonstrates the feasibility of characterizing the speeds of a moving phase boundary using atomistic simulations employing a suitable empirical potential for single-crystal magnesium. The model can provide temperature- and tensorial stress-dependent velocity of a moving phase boundary as a rate-limiting contribution to the kinetics of phase transformation in continuum codes. Results demonstrate that a nonlinear interaction exists between plasticity and phase transition, facilitating a jump in the velocity of a moving phase boundary, facilitated by activated plastic deformation mechanisms.