THE INVESTIGATION OF EXOTHERMIC BRAZING OF REFRACTORY ALLOYS.
Quarterly rept. no. 2, 1 Feb-30 Apr 63,
WHITTAKER CORP SAN DIEGO CALIF NARMCO RESEARCH AND DEVELOPMENT DIV
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Exothermic reactions internal exotherms that produce a braze alloy, a fluxing ceramic phase, and part of the heat required for brazing were investigated for brazing refractory metals. Acceptable joints were obtained with internal exotherms yielding a Ni-Mn braze alloy however, those designed to yield a more refractory alloy liquidus in excess of 3000 F were not success ful. Exothermic reactions external exotherms which act as a heat source were also investigated. Acceptable joints were obtained with W, Ta, Nb, Mo, and TZM alloy using braze filler alloys which melt at temperatures up to 3100 F. Data on the effect of the exothermic heating cycle on the various refractory base metals was obtained using tensile and microhardness evaluations as well as metallographic examination. Author