Molybdenum-copper cross-field amplifier radar waveguide braze joint

Brief reference back to a prior lecture's case. 82Au-18Ni braze of Mo to Cu formed Ni3Mo intermetallic, snapping at five degrees of bend. Reformulated to a low-Ni transient-liquid-phase braze (3% Ni, mostly Cu) — eliminated intermetallics, allowed 180° hairpin bend.

At higher temperatures you end up with — I told you about the problem when they were trying to braze the molybdenum to the copper for the cross-field amplifier for the radar. They originally had an 82 gold, 18 nickel braze, and they were forming nickel-three-moly intermetallic, and you get like five degrees bend and the whole thing would snap. Then they got to a transient liquid phase — they only had three percent nickel in their braze alloy, a lot less gold, a lot of copper. Formed a TLP bond with no intermetallics; you could bend the thing like a hairpin 180 degrees.