Regulation on microstructure and mechanical properties of SiC particles reinforced AZ31 magnesium matrix composites fabricated by synchronous feeding of powder and wire in wire-arc directed energy deposition

Ceramic particles reinforced magnesium matrix composites (CMMCs) have attracted widespread attention and investigation due to their excellent comprehensive performances. However, limited research on additive manufacturing of CMMCs has been performed. In this work, the SiC/AZ31 composites were fabricated by wire-arc directed energy deposition (WA-DED) based on the synchronous feeding strategy of powder and wire. The defects, SiC particle distribution, microstructure and mechanical properties of the prepared WA-DED SiC/AZ31 composites were studied. The results indicated that SiC particles with the content range of 0.3–1.7 wt% have been successfully added into the single-channel monolayer AZ31 matrix by adjusting the turret speed (TS) and the argon gas flow rate (AGFR) flowing through the powder feeder. The mathematical model is established to predict the introduced SiC particle content by correlating the relationship between SiC particle content and process parameters (TS and AGFR) of the powder feeder. The transformation from columnar to equiaxed grains occurs after adding SiC particles, more precipitated phases are formed after introducing more SiC particles. Compared to the AZ31 matrix, the WA-DED SiC/AZ31 composites exhibit the highest yield strength of 92.8 MPa and tensile strength of 213.3 MPa on the premise of almost no loss of elongation, and the maximum improvement efficiency of tensile strength reaches 56%, which is mainly ascribed to refinement strengthening, while thermal mismatch strengthening, Orowan strengthening and load-bearing strengthening play a booster action.