SUPERSOLIDUS-TRANSIENT LIQUID-PHASE SINTERING USING SUPERALLOY POWDERS

The sintering of nickel-base superalloy powders was studied for densification 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 sintering cycle. Processing variables such as composition, particle size ratio, packing density, sintering temperature, sintering time, and heating rate affected the sintering response. Starting with uncompacted powders, sintered densities as high as 96% of theoretical could be achieved by sintering in a hydrogen atmosphere and tailoring the processing conditions. The roles played by the alloying elements, especially boron, were studied with electron microprobe analysis. The concepts that emerge from this study can be used to understand the supersolidus liquid phase sintering response of complex multicomponent systems.