Ceramic cores for casting superalloys and refractory metal composites, and related processes

A method for casting a turbine component formed of a refractory metal intermetallic composite (RMIC) or superalloy material, comprising the following steps:

• (i) fabricating a core by:
• (a) combining at least one rare earth metal oxide, aluminum metal, and at least one binder, to form a ceramic mixture;
• (b) forming the ceramic mixture into a green product of an article-shaped body;
• and
• (c) heating the green product under conditions sufficient to form a sintered ceramic core which comprises after sintering, at least about 10% by weight of at least one monoclinic rare earth aluminate;
• and at least about 10% by weight, after sintering, of at least one free rare earth oxide.
• (ii) disposing the ceramic core in a pre-selected position within a shell mold;
• (iii) introducing a molten RMIC material or molten superalloy material into the shell mold;
• (iv) cooling the molten material, to form the turbine component within the shell mold;
• (v) separating the shell mold from the turbine component;
• and
• (vi) removing the core from the turbine component, so as to form selected interior cavities within the turbine component.