Additive manufacturing offers precise control over part geometry and material composition, making it ideal for creating functionally integrated materials (FIMs). A Ni-Al FIM was fabricated using directed energy deposition (DED) to investigate how local composition variations affect microstructure, precipitation, and mechanical behavior. Advanced microscopy characterization revealed a novel grain structure with distinct compositional regions and a composition transition interface. These distinct regions within a single grain led to abrupt changes in the deformation response, as demonstrated through in-situ micropillar compression. These findings underscore the potential of additive manufacturing to engineer material behavior at the microscale, advancing materials design and manufacturing. Towards additive manufacturing of functionally integrated materials, this study explores a novel approach to engineering the microstructure and mechanical behavior via spatial control of alloy composition within a single grain.