OBSERVATION OF GRAIN-BOUNDARY STRUCTURE FEATURES IN ALUMINIUM ALLOYS BY MEANS OF XAS AND X-RAY TOMOGRAPHY BY SR
- Dr. Alexander NIZOVSKII
- Dr. Alexander NIZOVSKII (Boreskov Institute of Catalysis)
Aluminum and its alloys are considered to be the promising agents for hydrogen production in reaction with water to use them in compact fuel cells. The only problem is to increase their reactivity. One of the methods of activation is the treatment of aluminum by gallium-based liquid metal eutectics. Previously, we noted that the process of activating the aluminum alloys was associated with the grain boundary diffusion of the eutectic components. To determine the nature of high reactivity of the activated material in reaction with water, a number of commercial aluminum alloys were studied with the help of the methods of XAS and X-Ray tomography by SR after activation. It was shown that the highly active state was associated with the formation of the nanostructured material, wherein the components of Ga-In eutectic distributed throughout the grain boundaries in the all the mass of the original sample. To confirm this observation, the aluminum alloys with different grain boundary structures have been investigated including those having high reactivity as well as the samples which lost the activity during prolonged storage under atmospheric conditions. Using X-ray tomography by SR, it was shown that in all the highly reactive samples, the components of Ga-In eutectic were distributed in the grain boundaries of the entire material. The activated samples, in which the components were not evenly distributed, did not completely dissolve in water. By XAS method, it has been found that in the highly active material, the eutectic components were in metallic state. Deactivation during prolonged storage under atmospheric conditions was associated with oxidation of the components of the eutectic alloy. It is shown that the distribution of the eutectic component in the sample is determined by the grain boundary structure of the initial material.