Al-Li Surface Alloying in the Electrolytic Method
Surface alloying is a new method of surface treatment by which an element is diffused into the surface of another element causing the formation of a solid solution on its surface. Using this method, the problems of casting methods have been eliminated. In this method, the sample is sunk into an aqueous solution and is connected to the cathode. Applying enough voltage, lithium separated from lithium sulphat-sulfuric acid solution diffuses into the aluminum surface. The depth of diffusion into the aluminum is measured to be 50 to 500μm according to the diffusion time which is selected to be 1 to 24 hours. Experiments showed that the formed layer is very uniform. It was also concluded from the experiments that hardness is increased extensively, with the maximum value of 98HV, and fatigue life is increased by the factor 4. It was also shown that the toughness, yield stress and ultimate tensile strength of samples are the same as those of pure aluminum.
Andreas Öchsner and Graeme E. Murch
I. Foroutan et al., "Al-Li Surface Alloying in the Electrolytic Method", Defect and Diffusion Forum, Vols. 273-276, pp. 531-535, 2008