A process for filling openings, including blind holes, through-holes, and cavities, in high temperature components. The process entails forming a powder mixture by mixing particles of at least a base alloy and a second alloy that contains a sufficient amount of a melting point depressant to have a lower melting temperature than the base alloy. The powder mixture is combined with a binder and compacted to form a compacted preform, which is then heated to remove the binder and form a rigid sintered preform. The sintered preform is produced, or optionally is further shaped, to have a cross-sectional shape and dimensions to achieve a clearance of up to 200 micrometers with the opening, after which the preform is placed in the opening and diffusion bonded within the opening to form a brazement comprising the particles of the base alloy dispersed in a matrix formed by the second alloy.