Process of filling openings in a component

A process of filling a hole in a surface of a hot gas path component of a gas turbine, the component being cast from a nickel- or cobalt-base alloy and the hole being formed by a rod that supported a core within the component during casting of the component wherein the hole has an axial direction and a wall parallel to the axial direction and defining a cross-sectional shape of the hole perpendicular to the axial direction, the process comprising:

• forming the hole to have at least one interlocking feature separated from the surface of the component by the wall of the hole, the interlocking feature comprising a recess that diverges from the hole in a direction perpendicular to the axial direction of the hole;
• forming a powder mixture by mixing particles of at least a base alloy and a second alloy, the base alloy constituting about 30 to about 90 weight percent of the powder mixture, the second alloy containing a sufficient amount of a melting point depressant to have a lower melting temperature than the base alloy;
• combining the powder mixture with a binder and then compacting the combined powder mixture and binder to form a compacted preform;
• heating the powder mixture to remove the binder and form a sintered preform having a cross-section larger than the hole;
• shaping the sintered preform to produce a cross-sectional shape and dimensions to achieve a diametrical clearance of not greater than 200 micrometers with the hole;
• placing the sintered preform within the hole so that a perimeter thereof is surrounded by the wall of the hole and the sintered preform at least partially fills the hole, wherein the perimeter defines a cross-sectional shape of the sintered preform that corresponds to the cross-sectional shape of the hole and has dimensions to achieve a clearance of not greater than 200 micrometers between the perimeter of the sintered preform and the wall of the hole;
• and then
• diffusion braze bonding the sintered preform within the hole to at least partially fill the hole with a brazement comprising the particles of the base alloy dispersed in a matrix formed by the second alloy, wherein during the diffusion braze bonding step the sintered preform flows from the perimeter thereof into the recess and following the diffusion braze bonding step the brazement has a protrusion that extends into the recess and increases the shear surface area of a bond between the brazement and the wall of the hole.