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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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Methods of applying iridium to refractory metal substrate, chemical and mechanical behavior of coating substrate system, and qualitative oxidation tests
Mechanical twinning for improving creep strength and low temperature ductility of refractory metals
Lithium-boiling potassium refractory metal Rankine cycle power system heat transfer models
Weldability and elevated temperature stability of refractory metal alloys
Evaluation testing of protective coatings on refractory metals for nozzles and chambers
High temperature protective coating for refractory metals - electrodeposition and diffusion bonding of iridium on tantalum to prevent oxidation
Solubility and corrosion resistance of refractory metals and alloys determined in liquid alkali metals
Protective coating systems for refractory metal used in rocket engine nozzles - rocket engine test firing
Multi-principal-element alloys (MPEAs) based on 3d-transition metals show remarkable mechanical properties. In this study, the stacking fault energy (SFE) in face-centered cubic (fcc) alloys is a critical property that controls underlying deformation mechanisms and mechanical response. Here, we present an exhaustive density-functional theory study on refractory- and copper-reinforced Cantor-based systems to ascertain the effects of refractory metal chemistry on SFE. We find that even a small percent change in refractory metal composition significantly changes SFEs, which correlates favorably with features like electronegativity variance, size effect, and heat of fusion. For fcc MPEAs, we also detail the changes in mechanical properties, such as bulk, Young's, and shear moduli, as well as yield strength. A Labusch-type solute-solution-strengthening model was used to evaluate the temperature-dependent yield strength, which, combined with SFE, provides a design guide for high-performance alloys. We also analyzed the electronic structures of two down-selected alloys to reveal the underlying origin of optimal SFE and strength range in refractory-reinforced fcc MPEAs. These new insights on tuning SFEs and modifying composition-structure-property correlation in refractory- and copper-reinforced MPEAs by chemical disorder, provide a chemical route to tune twinning- and transformation-induced plasticity behavior in fcc MPEAs.
Effects of hydrostatic pressure on mechanical behavior of body centered cubic refractory metals and alloys
High temperature properties of binary and ternary cobalt-refractory-metal alloys, with special attention to carbon and zirconium addition effects on rupture life of the alloys
Applicability of iridium as protective coating for refractory metals - rates of interdiffusion of iridium with tungsten, molybdenum, and niobium
A compilation of eutectics and melting-point minima for binary combinations of metals having vapor pressures below 10 to the minus 10th power torr at 1500 degrees K and .00005 torr at 2000 degree K is presented. These compositions and others near them on their phase diagrams are potential special brazing fillers for refractory metals. Some possible problems and advantages for fusion bonds of such mixtures are indicated. Evaluations of brazing fillers containing refractory metals are reported.
Stress-rupture properties of composites containing refractory metal fibers and nickel alloys evaluated at high temperatures
Plating process welds, bonds, and seals refractory metals without weakening or changing the structure of the base metals. A metal halide compound in the vapor phase is decomposed to deposit filler metal on the base metal. The resulting bond is a true metal-to-metal bond.
Solubility of refractory metals and alloys in liquid potassium and lithium
Refractory metals interactions with gases in vacuum and inert gas environment, noting temperature and pressure effects on reactions, extent and kinetics
Contamination of refractory metals by oxygen, water vapor, and carbon monoxide