| Abstract Scope |
Additive friction stir deposition, leveraged to build the world’s largest metal 3D printer, is an innovative solid-state process known for its high build rate, excellent scalability, and superior as-printed quality. Particularly advantageous for printing high-performance Al alloys prone to hot cracking, this deformation-based process readily constructs large-scale Al components consisting of functionally graded or alternating layers. Here, large builds of alternating dissimilar Al alloys (AA2024/AA6061) are demonstrated, with material flow, morphology, and microstructural evolution examined for builds consisting of 1, 2, 3, 4, 5, and 6 layers. X-ray computed tomography and scanning electron microscopy reveal asymmetrical material flow and non-uniform material distribution in three dimensions due to bi-directional deposition. Continuous dynamic recrystallization is identified as the main grain refinement mechanism for both alloys, with B/B̅ and C types as the primary shear textures. Subtle precipitate evolution from reheating effects is revealed, leading to non-uniform hardness along the build direction. |