Additive friction stir deposition is an emerging solid-state additive manufacturing technology that has shown promise for bulk fabrication of metals and metal-matrix composites. Here, we perform a preliminary investigation into the influence of tool geometries on the particle distribution and matrix-particle coherence of SiC in the matrix of Aluminum Alloy 6061 and commercially pure Copper. Two tool geometries have been used: (1) a simple, featureless tool and (2) a complex geometry tool with four surface protrusions. For the simple tool geometry, the Al-SiC is observed to have less uniform bulk distribution of the reinforcement phase, resulting in regions of highly concentrated SiC reinforcement (up to 69 area%). The Cu-SiC sample produced with the simple geometry tool has a homogeneous distribution. The samples produced with the complex geometry tool show more uniform distribution of SiC reinforcement throughout the bulk of the deposit with local reinforcement concentrations reaching up to 42 area% and 28 area% for the Al and Cu matrix, respectively. All tool geometries create samples with good interfaces that have continuous contact between the particle and matrix phases, even including particles with sharp angles and non-spherical surfaces. Further optimization of tool geometries and processing conditions can lead to improved control of the reinforcement phase distribution and enable design of metal-matrix composites with tailored site-specific properties.

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