Influence of Impurities on Mechanical Properties of Electrodeposited Bulk Nanocrystalline Al

Abstract

Effect of typical impurities such as Fe, S, and Cl on mechanical properties of Al electrodeposited from a dimethylsulfone bath (DMSO2 bath) were studied. Electrodeposition from a DMSO2 bath was conducted to produce the bulk specimens with 0.08–0.24 at.% Fe, 0.47–0.84 at.% S, and 0.59–1.06 at.% Cl, varying the purity of aluminum chloride and current density. Decreasing the current density increased S contents and Cl contents, while the purity of aluminum chloride had no effect on chemical composition of the electrodeposits. The grain sizes were approximately 40–70 nm for Al electrodeposited from a DMSO2 bath. The grain sizes decreased with increase in S contents and Cl contents. The electrodeposited bulk nanocrystalline Al exhibited hardness values of 1.56–1.92 GPa. These values were higher than predicted values based on Hall–Petch equation of pure Al. Lattice parameter of samples was less than pure Al. According to Vegard’s law, Fe solute decreases the lattice parameter of Al. These results indicated that the hardness of the electrodeposited bulk nanocrystalline Al was affected by the reduction in the grain size and solid solution strengthening from the Fe contaminant.