Casting methods and molded articles produced therefrom

A method comprising:

• introducing the first casting material into a casting mold;
• applying directional solidification to the first casting material in the casting mold;
• introducing the second casting material into the casting mold, the second casting material having a different chemical composition than the first casting material;
• applying directional solidification to the second casting material in the casting mold;
• and
• forming the molded article, wherein the molded article comprises the first region formed by the first casting material and the second region formed by mixing a molten or liquid portion of the first casting material and the second casting material and the first region and the second region are cast as one integral casting,
• wherein the second region has at least one improved physical property relative to the first region, the physical property being one of oxidation or corrosion resistance, wear resistance, low cycle fatigue or strain, degree of isothermal creep rupture, tensile strength, weldability, high temperature resistance, thermal cracking, or material loss, and
• wherein the first region and the second region have different microstructure patterns.

A molded turbine bucket for use in a gas turbine engine, the turbine bucket comprising:

• a hub;
• and
• a blade, the blade including
• a first region formed by a first casting material, wherein the first casting material is a molten, liquid or fluid metal alloy;
• and
• a second region formed by mixing a molten or liquid portion of the first casting material and a second casting material, wherein the second casting material is a molten or fluid metal alloy,
• wherein the first casting material has a different chemical composition than the second casting material,
• wherein the first region and the second region have different microstructure patterns,
• wherein the first region and the second region are cast as one integral casting using directional solidification,
• wherein the molded article has a lower concentration of impurities than were present in the first casting material and the second casting material, and
• wherein the second region corresponds to a tip portion of the blade and the first region corresponds to the remaining balance of the blade, and wherein an interface between the first region and second region is devoid of an oxidation layer.