Synthesis and characterization of Ni-Mo filler brazing alloy for Mo-W joining for microwave tube technology

Abstract

A brazing process based on Ni-Mo alloy was developed to join porous tungsten cathode bottom and dense molybdenum cathode body for microwave tubes manufacture. The Ni-Mo alloy was obtained by mixing and milling powders in the eutectic composition, and applied on the surface of the components. The brazing was made at 1400 °C by using induction heating in hydrogen for 5 minutes. Alumina surfaces were coated with the binder and analyzed by Energy Dispersive X-rays Fluorescence. The brazed samples were analyzed by Scanning Electron Microscopy coupled to Energy Dispersive Spectroscopy. Stress-strain tests were performed to determine the mechanical behavior of the joining. The quality of the brazing was evaluated by assuring the presence of a "meniscus" formed by the Ni-Mo alloy on the border of the tungsten and molybdenum joint, the absence of microstructural defects in the interface between the tungsten and molybdenum alloys, and the adhesion of the brazed components.

Contributors to fluxgate magnetic noise in permalloy foils including a potential new copper alloy regime

“…The base powders combined to form a single uniform ingot (Fig. 1b) -the higher melting point molybdenum dissolving in the other liquid metals (e.g., Sene and Motta, 2013). Small cavities in the ingot were sometimes observed in the face contacting the crucible.…”

Metallurgical Processing for Impregnated Thermionic Cathodes Manufacturing

“…A processing improvement was obtained by changing the graphite crucible used to heat the samples for a molybdenum one 9,12 . A general design of the new crucible can be seen in Figure 8.…”

Contributors to Fluxgate Magnetic Noise in Permalloy Foils Including a Potential New Copper Alloy Regime

“…The process furnace ramped from room temperature to 1550 °C at 300 °C/hour, held for one hour duration, and then returned to room temperature at 300 °C/h. The base powders combined to form a single uniform ingot (Figure 1b) -the higher melting point 55 molybdenum dissolving in the other liquid metals (e.g., Sene and Motta, 2013). Small cavities in the ingot were sometimes observed in the face contacting the crucible.…”