Abstract: An improved method of casting an article decreases the time required to cast the article without affecting the quality of the article. When a directionally solidified (DS) casting is made, molten metal is poured into a mold cavity. One end of the mold cavity is exposed to a chill plate which initiates solidification of the molten metal. As the metal solidifies, a dendritic structure grows upwardly into the mold cavity. Molten metal is disposed in the interstices of the uppermost portions of dendritic structure. As the metal in the mold cavity cools, the molten metal in the interstices solidifies and the dendritic structure, including a region containing some molten metal in the interstices, continues to grow upwardly toward the upper end of the mold cavity. The directional solidification of the metal in the mold cavity is promoted by slowly withdrawing the mold from a furnace as the molten metal solidifies.

Abstract: An improved method of casting an article includes using the same starter element during the casting of a plurality of metal articles. In one specific instance the starter element consisted of a single metal crystal. The single crystal starter element was used to initiate the solidification of molten metal in a mold to form a single crystal cast article. This was done without significant bonding between the solidified metal and the single crystal starter element. Therefore, the starter element could be separated from the solidified body of metal and subsequently used in the casting of another article. In order to tend to maximize the rate of heat transfer from the starter element and to tend to minimize bonding of the molten metal with the starter element, the starter element is advantageously located in a recess in a chill block with an upper surface of the starter element even with an upper surface of the chill block.

Abstract: 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.