Thixoforming of magnesium alloys and application to automotive industry

Abstract

The use of magnesium alloys in the automtive field is increasing due to their lightness. At present most widespread applications regard non structural components manufactured by high pressure die casting. New forming technologies are now growing aimed at producing structural components which have to meet more severe targets: thixoforming seems to be the most attractive. In this near-net shape process the metal in the semi solid state fills the die with a laminar flow, preventing any gas entrapment in the final component. Besides the high quality reachable in the as cast part, it is possible to improve the mechanical properties by heat treatments. Other advantages of this technology are: energy saving, tighter part tolerances, less machining operations, no dangerous molten metal handling. Till now Thixoforming has been used for the production of aluminium automotive components, even of big dimensions, whereas only some prototypes of small parts were made of Mg-alloys.

At present some experiments are on going in order to evaluate the thixoformability of the AZ91 alloy for the manufacturing of structural magnesium components.

By means of this innovative process a variety of new application of magnesium alloys in the automotive sector can be envisaged for the next future.