Abstract The vast majority of advanced industrialized products are formed from the joining of individual components. However, when the joining must be permanent, welding is one of the most used processes. Among the welding processes, the Friction Stir Welding (FSW) process stands out in this category specially for producing joints with extremely high mechanical resistance and low distortions leading to modern automotive and aerospace applications. This study aimed to evaluate the mechanical and corrosion properties of FSW welded profiles of Aluminum AA6005 alloy as a function of the welding parameters. For this purpose, tensile and microhardness tests were performed, followed by a detailed microstructural analysis. The results showed that the high rotational speed provided tunnel-type defects which impair the mechanical properties, leading to a loss of efficiency. The corrosion properties results showed that the different welding conditions do not significantly affect corrosion characteristics but the changes observed are related to the dispersion of the precipitates in the Al matrix.

In this study, we have investigated the synthesis, microstructure and hydrogen storage properties of Mg-based nanocomposites containing different concentrations of TiCrV and TiCr1.2V0.8 alloys. The Mg-based nanocomposites of Mg containing Ti-Cr-V additives were prepared by reactive milling (RM) under hydrogen atmosphere. The structural characterization revealed the presence of the β-MgH2, γ-MgH2 and BCC phases in the powders samples after RM. In addition, a very refined and homogenous microstructure with average MgH2 crystallite size of around 10-12 nm was observed, including a nanometric dispersion of the additives in the magnesium hydride matrix. The doping with TiCrV and TiCr1,2V0,8 greatly improves the hydrogen desorption behavior of Mg in comparison with the sample without additive, resulting in the lowest onset temperature (240 ºC) for the sample containing 5%mol. of TiCrV. Very fast absorption and desorption kinetics at 275 ºC and 300 ºC (7 minutes and 5 minutes for full desorption and absorption, respectively) were observed in the samples containing TiCrV and TiCr1,2V0,8 without any notable difference between the type of additive used in comparison with the pure sample. However, a slight reduction in hydrogen capacity is observed in the mixtures than for the pure sample (6.7 wt.% against 7.3 wt.%).

MgH2 was processed by short time high-energy ball milling (BM) and cold rolling (CR). A new alternative processing route (CR + BM) using the combination of CR followed by short time BM step was also applied. The effects on the final morphology, crystalline structure and H-sorption properties were evaluated. The CR + BM processing (compared to BM and CR process) resulted in an inhomogeneous particle size distribution and the biggest crystallite size of MgH2, showing that there is a clear dependence between the size/shape of the particles which compose the starting material and the efficiency of crystallite size reduction during the BM process. On the other hand, we observed that a short BM step improved the kinetic properties of the cold rolled material. It shows that the particle size reduction of MgH2 obtained by CR combined with the increase in specific surface area attained by short BM step could be key factors to allow the use of the CR + BM route.