Silica particulate dispersion during additive friction deposition in a metal matrix composite

This work presents a study of a low-power, solid-state additive manufacturing process to simultaneously mix and build a metal matrix composite. Specifically, an Al 6061 powder was blended with 11 wt% silica (SiO2) after which the powders were solid-state consolidated through additive friction stir deposition (AFSD). The inclusion of the SiO2 resulted in an average hardness of 70 +/- 1 HV as compared to a control (no SiO2) of 52 +/- 1 Hv. However, for the SiO2 composite, the hardness varied in both the radial build and vertical build directions, with the highest hardness found in the centerline of the deposit. This inhomogeneity has been contributed to differences in how the SiO2 particulates evolve during the stirring and mixing processes of AFSD. Furthermore, this variation in particulate evolution was found to be a useful marker in understanding the microstructure evolution through AFSD.