Nanomechanical Characterization of Functionally Graded Al-Fe MMC Processed by Additive Friction Stir Processing

The Solid State Additive Manufacturing (SSAM) process referred to as Additive Friction Stir (AFS) provides a new path for repair, coating, joining and additively manufacturing materials such as functionally graded metal matrix composites (MMC). This additive manufacturing process differs from traditional friction stir welding since metal powder or solid rod is fed through a non-consumable rotating cylindrical tool generating heat and plastically deforming the feedstock material through controlled pressure from the tool as successive layers are built upon a substrate. In this research, aluminum powder was mixed with iron particles and deposited on an 1100 aluminum alloy substrate with the iron content varying from 2%-iron at the base to 24%-iron at the top of the build. Nanoindentation performed on the deposited MMC was spatially correlated to scanning electron microscopy – energy dispersive X-ray spectroscopy (SEM-EDX) to provide a relationship of the nanomechanical modulus and hardness to the indent chemical composition.