Low temperature rolling of AZ91 alloy for hydrogen storage

R.FLORIANO; D.R.LEIVA; G.C.MELO; T.T.ISHIKAWA; J.HOUT; M.KAUFMAN; S.J.A.FIGUEROA; L.A.MENDOZA-ZÉLIS; W.J.BOTTA; L.C. DAMONTE

INTERNATIONAL JOURNAL OF HYDROGEN ENERGY

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2017 p. 29394 - 29405

0360-3199

The hydrogen storage properties of a commercial AZ91 magnesium alloy were investigatedafter processing by cold rolling in two different conditions: (a) extensive cold rolling at roomtemperature (CR); (b) rolling with the immersion of the alloy in liquid nitrogen bath after 05rolling passes. This second condition is named as low temperature rolling (LTR). A fullmicrostructural characterization including scanning and transmission electron microscopy(SEM and TEM), X-ray diffraction (XRD), X-ray photoelectron and positron annihilation lifetime spectroscopy (XPS and PALS) were performed in the processed alloys. The hydrogenstorage properties weremeasured using a Sievert-type apparatus. The AZ91-alloy is composedby the b-Mg and Mg17Al12 phases, and after processing by CR, an intense peak broadening andstrong [002] texture were observed in the alloys. The LTR processing resulted in a more fragilematerial containing more microcracks and exposed interfaces than the conventionally coldrolled one. The LTR sample also presented a more refined microstructure in comparison withCR sample. These features resulted in superior hydrogen storage properties for the LTR samplein comparison with the CR sample. In addition, the effect of surface contamination was alsostudied in detail and it was found to play a significant role during the activation kinetics