Browsing by Keyword "Magnesium"
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Item Investigation of HVOF spraying on magnesium alloys(2006-12-04) Parco, Maria; Zhao, Lidong; Zwick, Jochen; Bobzin, Kirsten; Lugscheider, Erich; EXTREMATMagnesium alloys are promising alternatives to other lightweight alloys such as aluminum alloys due to their high specific strength and stiffness. However, the use of magnesium alloys is limited by their poor wear behaviour and corrosion performance. Recent studies have shown an enormous potential of thermal spray techniques for the surface modification of Mg alloys. The high particle velocities and moderate temperatures achieved by the High Velocity Oxy-Fuel (HVOF) flame spray process lead to very dense coatings with outstanding wear behaviour and superior bond strengths in comparison to other thermal spray processes. In this study, two Mg alloys AZ91 and AE42 were coated using the HVOF spray process. The substrates were compared in terms of the measured bond strength and the observed adhesion mechanisms of the coating. Furthermore, the coatings were characterized concerning their corrosion performance on AZ91 substrates. It was found that dense WC-Co coatings could be applied on Mg alloy substrates using the HVOF spray process. The high kinetic energy of the WC-Co particles led to a "self roughening" effect on the substrate, enabling the deposition on polished Mg alloy substrates. The coatings showed a very good adhesion to the substrates. The corrosion tests showed that the unsealed WC-Co coatings could not improve the corrosion performance of Mg alloys. In contrast, the duplex coating system with an Al bond coat improved significantly the corrosion resistance of Mg alloys. The sealed coatings showed a very good corrosion behaviour.Item Modelling of Light Mg and Al Based Alloys as “in situ” Composites(SPRINGER INT PUBLISHING AG, GEWERBESTRASSE 11, CHAM, CH-6330, SWITZERLAND, 2017-10-26) Parashkevova, Ludmila; Egizabal, Pedro; Todorov, Michail; Georgiev, Ivan; Georgiev, Krassimir; Georgiev, Ivan; Tecnalia Research & InnovationThe present paper is aimed to further elucidate the microstructure properties relationship of light alloys containing additional hard particles. The materials studded are magnesium alloys from the system AZ (Mg–Al–Mn–Zn) and mechanically alloyed aluminum reinforced with carbide and oxide particles. Strengthening and hardening phenomena in Metal Matrix Multiphase heterogeneous Materials (MMMM) are considered in this study from the view point of mechanics of nano- and micro-composites. A semi-analytical approach is adopted taking into account the manufacturing processing and microstructure features. Multilevel homogenization procedure is performed, accounting for size effects. In the model applied the metal matrix is considered as an elastic–plastic micropolar media and the hard phases (precipitations Mg17Al12, TiC, Al4C3, Al2O3) are treated as conventional elastic Cauchy materials. Experimentally observed dependence of the characteristic matrix length on the volume fraction of the hardening phases is modeled and numerically simulated in the case of ball-milled Al alloyed with Al4C3 and Al2O3. For AZ alloys the impact of intermetallic phase Mg17Al12 is discussed in the frame of presented composite model and the strengthening effect of the addition of small amount of TiC is estimated.Item Technical and environmental evaluation of a new high performance material based on magnesium alloy reinforced with submicrometre-sized TiC particles to develop automotive lightweight components and make transport sector more sustainable(2019-05) Ferreira, Victor; Merchán, Mikel; Egizabal, Pedro; García de Cortázar, Maider; Irazustabarrena, Ane; López-Sabirón, Ana M.; Ferreira, German; CIRMETAL; Tecnalia Research & Innovation; SGThis study evaluated the use of submicrometre-sized particles based on titanium carbide from both technical and environmental points of view. The objective was to improve the mechanical properties of the magnesium alloy intended for use in the automotive component industry. To this end, an Al/TiC master compound containing 60 wt.% of TiC was produced through a self-propagating, high-temperature synthesis process and embedded in a magnesium alloy by a mechanical stirring method. The life cycle assessment methodology was then used to evaluate the environmental impact of the manufacturing of the magnesium alloy reinforced with submicrometre-sized particles. X-ray diffraction and scanning electron microscopy techniques revealed the nature and purity of the TiC present in the material and revealed particle sizes below submicrometre range (300–500 nm). The incorporation of TiC particles into the magnesium alloy resulted in improvements in yield stress and ultimate tensile strength of more than 10% and 18%, respectively, and increases in ductility values by 30%. Finally, the results indicated that the submicrometre particle production had a low environmental impact compared with the total impact associated with manufacturing the magnesium alloy reinforced with submicrometre-sized particles; the greatest environmental burden was attributed to the magnesium production stage. However, this impact is offset in the use phase of the vehicle, providing approximately 28,000 km of mileage for a car.