Magnesium (Mg) is a light metal with relatively low cost. Its hydride (MgH2) is interesting for the safe hydrogen storage in solid state and has a high gravimetric capacity of 7.6%. Practical application of Mg is still hampered by high reaction temperatures and slow kinetics. In order to improve it and focus on more viable industrial processing conditions, Mg plates, with or without iron (Fe) addition, in the form of wires and powders, were submitted to severe plastic deformation (SPD) in air, starting with extensive cold rolling (ECR), followed by repetitive rolling (ARB). The samples were characterized by X-ray diffraction (XRD), optical microscopy (OM), scanning (SEM) and transmission electron microscopy (TEM). H2 storage properties were evaluated by differential scanning calorimetry (DSC) and Sievert's volumetric method. Mg processed by ECR+ARB resulted in larger grain refinement and densities of cracks than ECR. In addition, Fe in the form of continuous wires was fragmented and resulted in a better distribution of particles than powders, which agglomerated. Thus, finally, the synergetic effect of microstructural features and Fe as catalyst and its distribution improved activation, kinetics and hydrogen storage capacity.

Severe plastic deformation routes (SPD) have been shown to be attractive for short time preparation of magnesium alloys for hydrogen storage, generating refined microstructures and interesting hydrogen storage properties when compared to the same materials processed by high-energy ball milling (HEBM), but with the benefit of higher air resistance. In this study, we present results of a new processing route for Mg alloys for hydrogen storage: rapid solidification followed by cold work. A Mg97Ni3 alloy was processed by melt spinning (MS) and by extensive cold rolling (CR). Submitting Mg97Ni3 ribbons between steel plates to cold rolling has shown to be a viable procedure, producing a thin cold welded foil, with little material waste. The as-processed material presents a high level of [002] fiber texture, a sub microcrystalline grain structure with a high density of defects, and also a fine dispersion of Mg2Ni nanoparticles. This refined microstructure allied to the developed texture resulted in enhanced activation and H-sorption kinetics properties.

The aim of this work is to evaluate the conjugation of advanced processing techniques, such as spray forming, extrusion and ECAP as a processing route for reuse of machining chips generated during aircrafts manufacturing parts from AA7050-T7451 raw material plates supplied according to AMS 4050H¹. In this way, the sprayforming process was used for remelting, and billet production, followed by extrusion and ECAP. At the end of the process, an artificial aging according to AMS 2772E ² was conducted. An assessment of chemical composition, microstructure, and mechanical properties evolution throughout the process were performed. The results have showed that this proposed route may be used as a potential technological route for secondary aluminum source. For extrusion route for overaged condition, 144 MPa yield strength and 14% of elongation was attained. Beside this, at this stage of work, was verified that the hot extrusion process is more effective for reduction of porosity and microstructure development than ECAP, but on the other hand this one has reduced porosity dispersion significantly for the extrusion parameters adopted. The adopted homogenization schedule, followed by artificial aging after has resulted in excessive grain growth.

The compound Mg2FeH6 was synthesized from a 2Mg-Fe mixture in a single process through high-energy ball milling under hydrogen atmosphere at room temperature. The complex hydride was prepared from Mg powder and granulated or powdered Fe using a planetary mill. The phase evolution during different milling times was performed by X-rays diffraction technique. The dehydrogenation behavior of the hydride was investigated through simultaneous thermal analyses of differential scanning calorimetry and thermogravimetry coupled with mass spectrometer. The use of powdered iron as starting material promoted conversion to complex hydride at shorter milling times than when granulated iron was used, nevertheless, after 24 hours of milling the 2Mg-Fe (powdered or granulated) mixtures presented similar dehydrogenation behavior. The hydrogen absorption during milling was on average 3.2 wt. (%), however, changing the proportions of the reagents to 3Mg-Fe a Mg2FeH6-MgH2 based nanocomposite with higher density of hydrogen (5.2 wt. (%)) was obtained.