Effect of potential difference between nano-Al2O3 whisker and Mg matrix on the dispersion of Mg composites

The potential difference between positive and negative ions was utilized to improve the homogenized dispersion of nanoscale Al 2 O 3 whiskers in Mg matrix composites. The Mg powders were decorated with sodium dodecylbenzene sulfonate (C 18 H 29 NaO 3 S, SDBS) and were introduced to the cathode group on their surface. The Al 2 O 3 whiskers were modified by the cetyl trimethyl ammonium bromide (C 19 H 42 BrN, CTAB) and were featured in the anode group. The suitable contents of CTAB and SDBS, the application atmosphere, and the type of solvents were investigated. Dispersion results showed that adding 2wt% SDBS into Mg powders and adding 2wt% CTAB into Al 2 O 3 whiskers promoted the formation of more uniformly mixed composite powders, compared to those of conventional ball milling via scanning electron microscopy (SEM) analysis. Meanwhile, the calculated results derived from first-principle calculations also demonstrated the stronger cohesion between Al 2 O 3 whisker reinforcements and Mg matrix than undecorated composite powders. After preparation by powder metallurgy, the morphology, grain size, hardness, and standard deviation coefficient of composites were analyzed to evaluate the dispersed efficiency. The results indicated that the modification of homogenized dispersed Al 2 O 3 whiskers in composites contributed to the refinement of 26% in grain size and the improvement of 20% in hardness compared with pure Mg, and the reduction of 32.5% in the standard deviation coefficient of hardness compared with the ball-milling sample.