The present disclosure generally relates to methods of electro-depositing a crystalline layer of pure aluminum onto the surface of an aluminum alloy article. The methods may include positioning the article and an electrode in an electro-deposition solution. The electro-deposition solution includes one or more of an aluminum halide, an organic chloride salt, an aluminum reducing agent, a solvent such as a nitrile compound, and an alkali metal halide. The solution is blanketed with an inert gas, agitated, and a crystalline layer of aluminum is deposited on the article by applying a bias voltage to the article and the electrode.