Pre-electrodeposition process for improving tensile ductility of Al electrodeposited from a dimethylsulfone bath

Al was electrodeposited from a dimethylsulfone (DMSO2) bath using a new pre-electrodeposition process to investigate the effect of sulfur and chlorine on the tensile ductility. Al electrodeposited from a DMSO2 bath contains sulfur and chlorine, which are impurities are incorporated into the electrodeposits as sulfide and chloride, respectively. By pre-electrodeposition, the sulfur and chlorine contents of electrodeposited Al decreased from approximately 0.64 and 0.71 at% to 0.15 and 0.17 at%, respectively. This reduction in the sulfur and chlorine contents affects the microstructure, hardness, and ductility of the electrodeposits. The grain size increased from approximately 200 nm to 4 μm, and the microhardness decreased from 1.67 to 0.24 GPa. In tensile tests, electrodeposited Al before pre-electrodeposition exhibited failure even in the elastic regime, while electrodeposited Al after pre-electrodeposition exhibited good tensile ductility of approximately 30%.