A method for joining materials using additive friction stir techniques is provided. The method joins a material to a substrate, especially where the material to be joined and the substrate are dissimilar metals. One such method comprises (a) providing a substrate with one or more grooves; (b) rotating and translating an additive friction-stir tool relative to the substrate; (c) feeding a filler material through the additive friction-stir tool; and (d) depositing the filler material into the one or more grooves of the substrate. Translation and rotation of the tool causes heating and plastic deformation of the filler material, which flows into the grooves of the substrate resulting in an interlocking bond between the substrate and filler material. In embodiments, the depositing of the filler material causes deformation of the grooves in the substrate and an interlocking configuration between the grooves of the substrate and the filler material results.