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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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Electrical de-poling and re-poling of relaxor-PbTiO 3 piezoelectric single crystals without heat treatment
Re-poling of unexpected partially depoled piezoelectric materials conventionally needs to be first fully depoled through annealing above their Curie temperature to revive piezoelectric performances. Here, we investigated de-poling and re-poling of Pb(In 1/2 Nb 1/2 )O 3 -Pb(Mg 1/3 Nb 2/3 )O 3 -PbTiO 3 single crystals under electric fields at room temperature. We found that alternating current electric fields with amplitudes near the coercive field at low frequencies (<10 Hz) can be employed to successfully depolarize poled crystals at room temperature. We also demonstrated a reversible polarization switching process with a relaxor-PbTiO 3 single crystal ultrasound transducer without device performance degradations. This experimental observation is supported by phase-field simulation, showing that alternating current electric fields can readily induce de-poling at room temperature, while direct current electric fields induce a transient depoled state only within an uncontrollable short period of time. The findings suggest new strategies for unprecedented in-device tailoring of the polarization states of ferroelectric materials.
Heat Treatment Effects on Mechanical Properties of Wire Arc Additive Manufactured and Electron Beam Additive Manufactured Ti-6Al-4V.
Abstract not provided.
Heat Treatment Effects on Mechanical Properties of Wire Arc Additive Manufactured Ti-6Al-4V.
Abstract not provided.
Heat Treatment Effects on Mechanical Properties of Electron Beam Additive Manufactured Ti-6Al-4V.
Abstract not provided.
Custom Post-Process Heat Treatments to Eliminate Columnar Microstructure in W-DED Ti-6Al-4V
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Heat Treatment Effects on Creep, Tensile, and Microstructural Behavior of Additively Manufactured Titanium Alloys
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Radiological Characterization of Uranium Decay Products in LEU U-10Mo Before and After Heat Treatment
Fuel for the U.S. high-performance research reactor fleet is undergoing significant development as the United States moves away from using highly enriched uranium dispersion fuels. The proposed fuel is a high-density, low-enriched uranium (LEU, 19.75 wt% U 235) alloyed with ten weight percent molybdenum fuel (known as LEU U 10Mo). The LEU U 10Mo fuel samples studied in this report were made by down-blending highly enriched uranium with a master alloy, which is cast from molybdenum rods and depleted uranium, via vacuum induction melting and then casting.
Effect of Heat Treatment on Spallation of Additively manufactured AlSi10Mg
The eutectic alloy AlSi10Mg is commonly used for additive manufacturing (AM), as its high Si content improves printability. This abundance of Si forms Si-rich precipitates whose structure is heavily dependent on the thermal history and have been shown to strongly influence its mechanical properties. In this presentation we present the results of experiments to study the effect of the Si-structure on the equation of state and spallation strength of AM AlSi10Mg.
Modeling heat treatments of metals using SPPARKS/LAMMPS
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Investigation on high cycle fatigue performance of additively manufactured Alloys: Synergistic effects of surface finishing and Post-Heat treatment
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Stress corrosion cracking of titanium alloys heat treatment effects, SCC velocity in various solvents and electrochemical kinetics with Ti - 8-1-1 alloy Quarterly progress report, 1 Oct. - 31 Dec. 1966
Stress corrosion cracking of titanium alloys
Radio-frequency plasma and heat treatment of human fecal matter
Low temperature ashing of human feces for solid waste management onboard spacecraft
Exploratory study of mechanical properties and heat treatment of molybdenum-hafnium-carbon alloys
Mechanical properties of alloys molybdenum hafnium carbon compounds
Rene 41 heat treatment electron microscopy
Electron microscope helps prevent post-weld strain-age cracking of Rene 41 by identifying in advance microstructures that are detrimental to welding.
Metallographic studies of an iron-nickel meteorite following long-time heat treatments
Iron-nickel alloy phase and diffusion relationships, composition gradients and hardness variations involving long time metallic meteorite anneals
Autoclave heat treatment for prealloyed powder products
Technique could be applied directly to loose powders as part of hot pressing process of forming them to any required shapes. This would eliminate initial extrusion step commonly applied to prealloyed powders, substantially reduce cost of forming operation, and result in optimum properties.
Effect of autoclave heat treatments on the mechanical properties of the prealloyed powder cobalt-base alloy HS-31
The cobalt-base alloy HS-31 was atomized into powder and then consolidated by extrusion or by hot isostatic pressing (HIP) in an autoclave over a range of temperatures spanning the solidus, approximately 2340 F. Extrusions were subsequently autoclaved at the same conditions. Extrusions autoclaved at 2420 F had a life of 300 hours at 1200 F and 30 hours at 1800 F at stresses that result in a 10-hour life with cast HS-31. Superior stress rupture lives of autoclaved material are probably related to the solidification structure at the grain boundaries as well as to the increased grain size.