Synergistic strengthening of arc-directed energy deposited aluminum composites via nanoparticles and metastable phase precipitation

Particle-reinforced aluminum matrix composites (P-AMCs) with properties superior to those of conventional aluminum alloys can be rapidly printed via arc-directed energy deposition (arc-DED), but elemental segregation occurs in the printed components, and the enhancement of the mechanical properties of the materials is limited. In this study, P-AMC components containing nanoparticles were deposited and strengthened using a customized heat treatment process. A coherent Guinier–Preston (GP) zone and a semicoherent η' metastable phase (MgZn 2 type) combined with TiC nanoparticles to form a triple reinforcement. The strength of the alloy was enhanced by the synergistic effects of fine-grain strengthening, Orowan dislocation bypassing, and dislocation shearing. The average tensile strength of the sample could reach 581.3 ± 11.7 MPa, which is a 164 % performance enhancement over that of conventional particle-reinforced AMC arc-DED components. A tensile strength of 74 % was maintained at 200 °C, which resulted in superior elongation (9.43 % increase). This paper provides new concepts for the development of AMCs with high specific strength and excellent thermal stability.