Magnesium alloys have gained increasing interest in the past years due to their potential as implant materials. This interest is based on the fact that magnesium and its alloys are degradable during their time of service in the human body. Moreover magnesium alloys offer a property profile that is very close or even similar to that of human bone. The chemical composition triggers the resulting microstructure and features of degradation. In addition the entire manufacturing route is having an 2 influence on the morphology of the microstructure after processing. Therefore composition and manufacturing route have to be chosen carefully with regard to the requirements of an application. This paper will discuss the influence of composition and heat treatments on microstructure, mechanical properties and corrosion behaviour of cast Mg-Gd alloys. Recommendations will be given for the design of future degradable magnesium based implant materials.
The development of secondary magnesium alloys requires a completely different concept compared with standard alloys which obtain their corrosion resistance by reducing the levels of impurities below certain alloy and process depending limits. The present approach suitable for Mg-Al based cast and wrought alloys uses a new concept replacing the ß-phase by τ-phase, which is able to incorporate more impurities while being electrochemically less detrimental to the matrix. The overall experimental effort correlating composition, microstructure and corrosion resistance was reduced by using thermodynamic calculations to optimise the alloy composition. The outcome is a new, more impurity tolerant alloy class with a composition between the standard AZ and ZC systems having sufficient ductility and corrosion properties comparable to the high purity standard alloys.
With the development of new heat resistant magnesium alloys, the automotive industry has introduced several parts to the drive train. The rising number of large magnesium components will result in a higher quantity of automotive post consumer scrap. It was the aim of this work to find a reasonable alloy system for the recycling of these magnesium drive train components. A matrix of potential recycling alloys based on the magnesium alloy AM50 was prepared via permanent mould casting. The materials were investigated via tensile testing, creep tests and salt spray tests. Three alloys were selected for processing via high pressure die casting and the tests were repeated on the new materials. A promising system for recycling has been isolated and will be investigated more deeply for the influence of impurities. magnesium recycling, end-of-life vehicles, recycling alloy, post consumer scrap
The increasing use of magnesium castings for automotive components and the number of newly developed alloys raise the question of suitable recycling processes. Remelting offers a high potential of energy saving and thereby improves the live cycle balance of magnesium components. Effective recycling processes are likely to involve the mixing of different alloys but little is known about the interaction of alloying elements. In order to approach this issue, the influence of strontium, silicon and calcium on phase formation and mechanical properties of magnesium alloy AM50 has been investigated.After strontium addition, X-ray diffraction demonstrated the formation of the Al 4 Sr-and the Mg 17 Sr 2 -phase.However, after simultaneous alloying with strontium, silicon and calcium the ternary Zintl-phase Compared to the two strontium-containing phases, precipitates of the ternary Zintl-phase exhibit a rather compact morphology. This results in a higher elongation-at-fracture under tensile stress.
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