Method for improving metallurgical bond in bimetallic castings

摘要

Method for making a bicast article in which a solid metal preform is positioned in a mold and a molten metal is cast around portions of the preform which are exposed in the mold. In accordance with the present invention, the exposed portions are coated prior to the casting step with a boron containing alloy which is compatible with the preform and with the metal to be cast about it, the boron containing alloy having a melting range below the melting range of either the preform or the cast metal. The alloy also has a major ingredient which is the same as the major ingredient of at least one of the metals to be joined. After solidification of the molten metal in the casting cavity, the resulting bicast article is heat treated at a temperature below the melting range of either the preform or the solidified metal to cause diffusion of boron into the preform and into the solidified metal thereby providing an improved metallurgical bond.