Turbine airfoil component and method for making

An article comprising:

• an airfoil casting portion comprising a base section, a tip section opposite the base section in an axial direction along the airfoil casting portion, a leading edge section comprising a leading edge of the airfoil casting portion, and a trailing edge section comprising a trailing edge of the airfoil casting portion, opposite the leading edge section in a transverse direction along the airfoil casting portion;
• a shroud portion comprising columnar-grained material, the shroud portion disposed at the tip section and integral with the airfoil casting portion;
• and
• a platform portion comprising columnar-grained material, the platform section disposed at the base section and integral with the airfoil casting portion;
• wherein the airfoil casting portion further comprises a single-crystalline region comprising a single-crystalline material;
• and a columnar-grained region,
• the single-crystalline material is disposed at the leading edge of the airfoil casting portion, or at the trailing edge of the airfoil casting portion, or at both the leading edge and the trailing edge of the airfoil casting portion, and
• at least 10 percent of a solid cross-sectional area of airfoil casting portion, as measured at a midpoint between a base and a tip of the airfoil, comprises the single-crystalline material.

A method for fabricating an article, the method comprising:

• providing a quantity of molten metal;
• providing a mold defining an airfoil portion having an axial direction;
• a transverse direction;
• a leading edge section;
• and a trailing edge section,
• wherein the airfoil portion of the mold comprises a single-crystal growth region and a columnar growth region disposed along the transverse direction from the single crystal growth region;
• introducing the molten metal into the mold;
• and
• solidifying the metal such that a solidification front progresses in the axial direction to produce an airfoil casting portion comprising
• a single-crystalline region comprising a single-crystalline material;
• and
• a columnar-grained region, wherein
• the single-crystalline material is disposed at least at a leading edge of the airfoil casting portion, at a trailing edge of the airfoil casting portion, or both the leading edge and trailing edge of the airfoil casting portion.