Effect of cold rolling on the structure and hydrogen properties of AZ91 and AM60D magnesium alloys subjected to ECAP

Abstract

It is attainable obtaining an appreciable amelioration of the hydrogen storage ability in magnesium by settling on a suitable sequence of mechanical processing. It is plausible to predict that a reduction in grain size into nanocrystalline dimensions may predispose to a substantial improvement in the diffusion and thermo-dynamical properties in magnesium hydride. This may be realized by Severe Plastic Deformation (SPD). The use of cold rolling after ECAP, a kind of SPD, considerably increases the preferential texture for hydrogenation. In this research, the association of ECAP and cold rolling was used to process commercial AM60D and AZ91 extruded alloys in order to evaluate their use as hydrogen storage materials. The ECAP was conducted under distinct conditions of numbers of passes in order to attain different grain sizes. After ECAP, both materials were cold rolled with the same number of passes for comparison of hydrogenation absorption. Hydriding properties are enhanced by (0001) texture, which improved kinetics mainly in the initial stages of hydrogenation and was effective even with unfavorable grain size. However, the presence of precipitates limits the storing capacity. Finally, it was demonstrated that optimum sorption properties may be acquired with the synergy between fine grains and the best texture.

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Identifiers

ORCID for Terence G. Langdon: orcid.org/0000-0003-3541-9250

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