Additive manufacturing aluminum alloy matrix composites without a strength-ductility trade-off

Additive manufacturing (AM) offers an effective means of overcoming the strength-ductility trade-off of aluminum alloy matrix composites that are reinforced with in-situ TiB₂ and TiC particles. Powders of the composites are produced by gas atomization in the range of 16-65 µm for a good ability of printing. Laser powder bed fusion (LPBF) alters the reinforcing particles and, combined with a high cooling rate, promotes nucleation of aluminum grains in the melt pool, resulting in refined grains of both the matrix and the reinforcing particles. This process achieves a homogeneous dispersion of TiB₂ and TiC particles, increasing their ability in nucleating aluminum grains, which are refined to approximately 2 µm. As a result, the AM composites demonstrate superior toughness over their rolled matrices, respectively. Refining the particles and aluminum grains leads to 40% and 87% increases in ultimate tensile strength (UTS) and yield strength (YS), respectively, while maintaining the same elongation of 16% of AM Al-Mg products that are reinforced with TiC particles. Meanwhile, AM Al-Cu composites with TiB₂ particles also show significant increases, 59% and 88% increases in UTS and YS, respectively.