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Ischaemic heart diseases are a global health problem that have been increasing in the recent years [1]. Most of ischaemic heart diseases is caused by atherosclerosis, a clinical pathology characterized by the deposition of fatty material on the arteries walls what may lead to thickening, hardening and blocking of these blood vessels, reducing the blood flow. This situation can cause heart attack, stroke and, in extreme cases, death [1,2]. Procedures such as balloon angioplasty and stenting, bypass surgery and atherectomy may be used to repair a blocked artery. Balloon expandable stents are the most used technique [1]. Materials such as stainless steel, Niobium and CoCr alloys are the most used in stents manufacturing. However, in the last years, studies have been directed to the search and development of new materials, mainly biodegradables, once these solutions fulfil some unmet medical needs [3]. The application of biodegradable stents dispenses a second procedure to remove the device, once this is absorbed over time. Magnesium alloys are one of the options.The main purpose of this work is the study of an AZ31 magnesium alloy stent expansion behaviour, without considering the contact definitions, by using the finite element method.A simple geometry composed by lozenges was modelled and simulated in order to study the required expansion pressure, equivalent plastic strain and other performance parameters such as dogboning, foreshortening and recoil. The model has an inner diameter of 0,74 mm and a length of 10 mm and its results were compared with those of a Palmaz-Schatz model, aiming to conclude about which geometry presents better performance. Both models were tested for thicknesses of 0.1 mm and 0.2 mm.The obtained results showed that Lozenge model requires higher expansion pressures than Palmaz-Schatz model and has worse performance in terms of foreshortening. In terms of dogboning, the Lozenge model presents better results, especially for 0.1mm of thickness. In what concerns to recoil phenomenon, considering the longitudinal recoil, Palmaz-Schatz model presents most favourable values, although, for central and distal recoil, Lozenge model has better results.

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In this work, the effect of ultrasonic vibration during solidification on the aging kinetics of an AlSi7Mg alloy is investigated. With the ultrasonic equipment coupled to the mold walls, melt treatment was performed by two approaches: (i) fully above liquidus (>635 °C); and (ii) in the full range between liquidus and solidus (630 °C→ 550 °C). Cast samples were then subjected to T6 heat treatment for different aging times. It is shown that indirect ultrasound treatment increases the cooling rate while active. The eutectic Si was refined and further modified when ultrasound treatment was performed in the semisolid state. Due to the significant release of solute during the decomposition of π-Al8FeMg3Si6 into fine β-Al5FeSi, this has a significant impact in the solution stage. Ultrasound treatment fully above liquidus decreased the underaging time to 50% and peak aging time to 25% without compromising strength. The results suggest aging kinetics are correlated with a higher vacancy density and solute enrichment which favors Guinier–Preston (GP) zone formation. These findings show a promising route to tailor the aging kinetics in these alloys by selectively modifying phases and cooling rates.