METHOD OF SELECTIVE GRAIN GROWTH IN NICKEL-BASE SUPERALLOYS BY CONTROLLED BORON DIFFUSION

摘要

11 47,546 This is a method for producing a composite grain structure in nickel-base superalloy articles by causing a controlled amount of grain growth in selected regions. The method uses alloys containing 0.01-1.0 carbon and .02-.08 boron and a heat treatment in a non-reducing atmosphere after the alloy has been formed. The heat treatment causes diffusion of boron (but not carbon) in selected regions, lowering the amount of boron and causing controlled grain growth in these regions.