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Made available in DSpace on 2022-04-28T17:23:23Z (GMT). No. of bitstreams: 0 Previous issue date: 2022-01-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Brazilian Centre for Research in Energy and Materials (CNPEM) Brazilian Ministry for Science, Technology, Innovations and Communications (MCTIC) The hydrogen storage properties of pure magnesium and magnesium ZK60 alloy containing 2.5 wt% of mischmetal (Mm) processed by Cold Rolling (CR) and Low Temperature Rolling (LTR) were investigated. Before CR and LTR processing, Equal Channel Angular Pressing (ECAP) was employed in the alloys as an initial processing step to refine their microstructures. Microstructure findings showed that the ECAP+LTR route is more effective than the others to generate grain refinement - a desirable aspect in hydrogen storage materials. SEM and TEM results in combination with XPS analysis revealed that the ZK60 + 2.5 wt. % Mm alloy after being processed by ECAP + LTR had more refined grains (with sizes < 1 mu m) and exhibited superior resistance to the formation of oxides and/or hydroxides when compared with the pure magnesium alloy. The refined microstructures of the ECAP+LTR samples combined with the presence of highly oriented grains along to the (002) plane and large amount of defects - which are features associated to the LTR route - such as cracks and voids, resulted in a fast activation kinetics than for the samples processed by ECAP + CR route. Univ Fed Sao Carlos, Programa Posgrad Ciencia & Engn Mat, Rod Washington Luis,Km 235, BR-13565905 Sao Carlos, SP, Brazil Univ Fed Sao Carlos, Dept Engn Mat, Rod Washington Luis,Km 235, BR-13565905 Sao Carlos, SP, Brazil Univ Estadual Campinas UNICAMP, Fac Ciencias Aplicadas FCA, Pedro Zaccaria 1300, BR-13484350 Limeira, SP, Brazil Univ Estado Rio de Janeiro, Inst Politecn, Dept Mat, BR-28625570 Rio De Janeiro, RJ, Brazil Univ Estadual Paulista UNESP, Dept Engn Mecan, Ave Brasil 56, BR-15385000 Ilha Solteira, SP, Brazil Ctr Nacl Pesquisa Energia & Mat CNPEM, Lab Nacl Luz Sincrotron LNLS, BR-13083970 Campinas, SP, Brazil Univ Fed Vale Jequitinhonha & Mucuri, Inst Engn Ciencia & Tecnol IECT, Dept Engn Mat, Janauba, MG, Brazil Univ Estadual Paulista UNESP, Dept Engn Mecan, Ave Brasil 56, BR-15385000 Ilha Solteira, SP, Brazil FAPESP: 2013/05987-8 FAPESP: 2018/15968-4 CAPES: 001 Brazilian Ministry for Science, Technology, Innovations and Communications (MCTIC): XPS21358 Brazilian Ministry for Science, Technology, Innovations and Communications (MCTIC): MicroCT-19224

This work aimed to study the microstructural evolution of commercial aluminum alloy AA7050 in the solution treated condition (W) processed by equal channel angular pressing - ECAP. The analyses were made considering the effects of process parameters as temperature (Tamb and 150°C), processing route (A and B C) and number of passes. Optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used for microstructural characterization, and hardness tests for a preliminary assessment of mechanical properties. The results show that the refining of the microstructure by ECAP occurred by the formation of deformation bands, with the formation of dislocations cells and subgrains within these bands. The increase of the ECAP temperature led to the formation of more defined subgrains contours and intense precipitation of η phase in the form of spherical particles. The samples processed by Route B C present a more refined microstructure.