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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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At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Microstructurally-Inspired Strategies to Print Tantalum and Tantalum-Tungsten Alloys

The goal of this project is to investigate strategies to print tantalum and tantalumtungsten alloys, which are notoriously difficult to print with consistent results because of the sensitivity of the properties to small concentrations of interstitial impurities (particularly oxygen) and microstructure, and hence to processing conditions. In direct metal laser sintering (DMLS) Ta, a strong dependence of porosity, grain morphology and texture on processing conditions was found.

36 MATERIALS SCIENCE↗
NASA NTRS1966

Lower-cost tungsten-rhenium alloys

Tungsten-rhenium alloys with a substantially more dilute rhenium content have ductilities and other mechanical properties which compare favorably with the tungsten-rhenium alloys having much higher concentrations of the costly rhenium.

Klopp, W. D.↗
DOE OSTI2020

Plasma and X-ray radiation-induced damage mechanisms in a tungsten heavy alloy

Tungsten-based materials are among the main candidate plasma-facing materials for future fusion reactors where extreme conditions of thermomechanical stresses, radiation, and energetic particles must be withstood. Here a hybrid X-pinch platform combined with a pulsed power machine was used to study damage mechanisms in 90W–4Cu–6Ni tungsten heavy alloy as a result of exposure to high energy density plasma, X-ray radiation, and the resulting thermal shock. It was found that the plasma-facing surface of the material undergoes severe melting and ablation with the extent of ablation being higher in the Cu–Ni phase than the W particles. Rapid melting and solidification transform the W particles into fine dendrite morphologies embedded in the Cu–Ni solid solution. Cracking was also observed in the subsurface layers at the interfaces between the W particles and the Cu-rich phase of the Cu–Ni matrix. X-ray radiation, on the other hand, cause slight melting on the surface without significant ablation and no cracking.

36 MATERIALS SCIENCE↗
NASA NTRS1985

Interdiffusional effects between tungsten fibers and an iron-nickel-base alloy

Tungsten fibers in the INCOLOY 903 alloy were annealed for over 100 hours at 1038 C and 1200 C. It was found that interdiffusion results in the formation of a reaction zone. SEM-EDS probe analysis showed that the chemistries across this zone were constant, suggesting the zone was a compound phase. The composition of the compound was estimated to be that of a mu-type phase. The local chemistry (in atomic percent) at the reaction zone/alloy matrix interface was found to be approximately 8 pct W, 1.2 pct Nb, 40 pct Fe, 14 pct Co, and 36 pct Ni. In addition, recrystallization was observed in both the remaining tungsten fiber and the nearby INCOLOY 903 matrix after annealing at 1200 C, but not at 1038 C. The results of this study suggest that reaction zone growth kinetics can be minimized by the reduction of Co and Fe and the increase of W in the matrix alloy.

Caulfield, T.↗