Electrodeposition of aluminumtungsten alloy films using EMICAlCl3W6Cl12 ionic liquids of different compositions

Abstract

Electrodeposition of AlW alloy films with high W contents has been carried out using 1-ethyl-3-methylimidazolium chloride (EMIC)aluminum chloride (AlCl3) ionic liquids containing tungsten(II) chloride (W6Cl12). Although the corrosion resistance and hardness of the alloy films are expected to be improved with an increase in the W content, dense films with W contents higher than ∼12 at% have not been obtained by electrodeposition to date. This study has demonstrated that electrodeposition using a EMICAlCl3W6Cl12 bath with a lower AlCl3/EMIC molar ratio can yield AlW alloys with higher W contents. The maximum W content of the alloys electrodeposited using the EMIC1.5AlCl3 bath reached 19.4 at%. The alloy films with up to ∼18 at% W were dense and smooth, whereas those with > ∼18 at% W exhibited increased surface roughness. The hardness and Young's modulus of the dense and smooth 17.7 at% W film were determined by nano-indentation. The hardness of this film was confirmed to be higher than those of the AlW alloy films previously obtained from the EMIC-2AlCl3 baths.