Preparation and characterisation of nickel-based brazing powder: cobalt and chromium addition effects

ABSTRACT In the present work, three novel brazing powders were produced, in addition to a commercial composition, by the mechanical alloying (MA) method. Cobalt and chromium’s effects on the properties of brazing powder and related joints were investigated. The results showed that; with the addition of cobalt, the powder morphology went to a rounded and near-spherical shape after 15 milling hours, and the solidus significantly raised. Also, chromium shifted the melting range to higher temperatures. The powder with 6% cobalt and 14% chromium had more than 100°C higher solidus and a melting range of 20°C than the commercial BNi-2, ideal for working temperature of more than 1000°C. The shear strength results revealed that the addition of chromium and cobalt significantly promotes joint strength owing to the activation of the solid solution strengthening mechanism. Therefore, the novel synthesized brazing powders can be an excellent candidate for high temperature and corrosive operating environments.