Low temperature rolling of AZ91 alloy for hydrogen storage

The hydrogen storage properties of a commercial AZ91 magnesium alloy were investigated after processing by cold rolling in two different conditions: (a) extensive cold rolling at room temperature (CR); (b) rolling with the immersion of the alloy in liquid nitrogen bath after 05 rolling passes. This second condition is named as low temperature rolling (LTR). A full microstructural characterization including scanning and transmission electron microscopy (SEM and TEM), X-ray diffraction (XRD), X-ray photoelectron and positron annihilation life time spectroscopy (XPS and PALS) were performed in the processed alloys. The hydrogen storage properties were measured using a Sievert-type apparatus. The AZ91-alloy is composed by the β-Mg and Mg17Al12 phases, and after processing by CR, an intense peak broadening and strong [002] texture were observed in the alloys. The LTR processing resulted in a more fragile material containing more microcracks and exposed interfaces than the conventionally cold rolled one. The LTR sample also presented a more refined microstructure in comparison with CR sample. These features resulted in superior hydrogen storage properties for the LTR sample in comparison with the CR sample. In addition, the effect of surface contamination was also studied in detail and it was found to play a significant role during the activation kinetics.Fil: Floriano, R.. Universidade Estadual de Campinas; BrasilFil: Leiva, D. R.. Universidade Federal do São Carlos; BrasilFil: Melo, G. C.. Universidade Federal do São Carlos; BrasilFil: Ishikawa, T. T.. Universidade Federal do São Carlos; BrasilFil: Huot, J.. Universite Du Quebec A Trois-rivieres; CanadáFil: Kaufman, M.. Department of Metallurgical and Materials Engineering; Estados UnidosFil: Figueroa, S.J.A.. Centro Nacional de Pesquisa Em Energia E Materiais; BrasilFil: Mendoza Zélis, Luis Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: Damonte, Laura Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: Botta, W.J.. Universidade Federal do São Carlos; Brasi