SUPERSOLIDUS-TRANSIENT LIQUID-PHASE SINTERING USING SUPERALLOY POWDERS

The sintering of nickel-base superalloy powders was studied for densif ication and microstructural development using a mixture of two powders , one containing 2.3w/o boron. The system exhibited the possibility of both transient and supersolidus liquid phase sintering in a single si ntering cycle. Processing variables such as composition, particle size ratio, packing density, sintering temperature, sintering time, and he ating rate affected the sintering response. Starting with uncompacted powders, sintered densities as high as 96% of theoretical could be ach ieved by sintering in a hydrogen atmosphere and tailoring the processi ng conditions. The roles played by the alloying elements, especially b oron, were studied with electron microprobe analysis. The concepts tha t emerge from this study can be used to understand the supersolidus li quid phase sintering response of complex multicomponent systems.