| 摘要 |
<p>An improved method of casting a directionally solidified metal article, such as an airfoil, includes the steps of providing a directionally solidified starter element which is formed of a plurality of elongated metal crystals. In one specifiec preferred embodiment, each of the elongated metal crystals of the starter element is formed of a plurality of cubic unit cells having sides extending at an acute angle to the longitudinal axis of the crystal such that each cell is advantageously oriented with its [111] direction extending substantially parallel to the longitudinal axis of the elongated crystal. When an article is to be cast, the starter element is positioned at the lower end of a mold cavity and is exposed to a chill. Molten metal is poured into the mold cavity and is solidified. As this occurs, a cast article is formed of elongated crystals having longitudinal axis extending parallel to the longitudinal axes of the crystals in the starter element. Each of the elongated crystals in the cast article is formed of a plurality of cubic unit cells. The sides of the unit cells of the elongated crystals in the cast article have the same orientation as the sides of the unit cells in the elongated crystals of the starter element.</p> |
