Method and assembly for forming components having internal passages using a jacketed core

A method of forming a component having an internal passage defined therein, said method comprising:

• applying at least a first coating layer to an interior portion of a preformed hollow structure, wherein the hollow structure is formed from a first material that is metallic;
• after said applying the at least first coating layer, disposing an inner core within the hollow structure to form a jacketed core;
• positioning the jacketed core with respect to a mold;
• introducing a component material in a molten state into a cavity of the mold, such that a portion of the jacketed core is submerged, and such that the component material in the molten state contacts the first material along substantially an entire outer perimeter of the submerged portion of the jacketed core;
• and
• cooling the component material in the cavity to form the component, wherein the inner core is positioned to define the internal passage within the component, and at least a portion of the first coating material lines at least a portion of the internal passage.