A method of forming a component from a component material being an alloy and the component having an internal passage defined therein, said method comprising: positioning a jacketed core with respect to a mold, wherein the jacketed core includes: a hollow structure formed from a first material, wherein the first material is at least one constituent material of the alloy of the component material; an inner core disposed within the hollow structure; and a core channel that extends from at least a first end of the inner core through at least a portion of inner core; introducing the component material in a molten state into a cavity of the mold, such that the component material in the molten state at least partially absorbs the first material from the jacketed core within the cavity; cooling the component material in the cavity to form the component, wherein the inner core defines the internal passage within the component, and removing the inner core from the component to form the internal passage, characterized in that the method further comprises forming the jacketed core by: positioning a wire within the hollow structure, the wire formed from a second material; and adding an inner core material within the hollow structure after the wire is positioned, such that the inner core material fills in around the wire, wherein the inner core material forms the inner core and the wire defines the core channel within the inner core, and in that positioning the wire within the hollow structure comprises: threading the wire through a plurality of spacers; and positioning the spacers threaded with the wire within the hollow structure.. positioning a jacketed core with respect to a mold, wherein the jacketed core includes: a hollow structure formed from a first material, wherein the first material is at least one constituent material of the alloy of the component material; an inner core disposed within the hollow structure; and a core channel that extends from at least a first end of the inner core through at least a portion of inner core; a hollow structure formed from a first material, wherein the first material is at least one constituent material of the alloy of the component material; an inner core disposed within the hollow structure; and a core channel that extends from at least a first end of the inner core through at least a portion of inner core; introducing the component material in a molten state into a cavity of the mold, such that the component material in the molten state at least partially absorbs the first material from the jacketed core within the cavity; cooling the component material in the cavity to form the component, wherein the inner core defines the internal passage within the component, and removing the inner core from the component to form the internal passage, characterized in that the method further comprises forming the jacketed core by: positioning a wire within the hollow structure, the wire formed from a second material; and adding an inner core material within the hollow structure after the wire is positioned, such that the inner core material fills in around the wire, wherein the inner core material forms the inner core and the wire defines the core channel within the inner core, and in that positioning the wire within the hollow structure comprises: threading the wire through a plurality of spacers; and positioning the spacers threaded with the wire within the hollow structure.. positioning a wire within the hollow structure, the wire formed from a second material; and adding an inner core material within the hollow structure after the wire is positioned, such that the inner core material fills in around the wire, wherein the inner core material forms the inner core and the wire defines the core channel within the inner core, and in that positioning the wire within the hollow structure comprises: threading the wire through a plurality of spacers; and positioning the spacers threaded with the wire within the hollow structure.. threading the wire through a plurality of spacers; and positioning the spacers threaded with the wire within the hollow structure..