DOI: 10.1002/adem.200700154 Development of Investment-Casting Process of Mg-Alloys for Aerospace Applications** By Gurutze Arruebarrena,* Iñaki Hurtado, Jukka Väinölä, Celal Cingi, Sandor Dévényi, John Townsend, Sajid Mahmood, Achim Wendt, Konrad Weiss and Arye Ben-Dov 1. Introduction Investment casting offers high-quality castings with good dimensional accuracy, being therefore suitable for aircraft applications. Due to the facts that commercial ceramic shells react with Mg melts and that appropriate inhibitors are not available, magnesium alloys are not widely used in industrial investment-casting. In order to overcome this situation and enable the aircraft industry to take advantage of the light weight properties of magnesium, the process is analyzed within the European FP6 IDEA project, which aims at devel- oping new high-strength magnesium casting alloys for aero- nautic applications. The aspects of the project considered in this paper are: – Study of metal-mould reactions with the purpose of developing a new shell for Mg investment-casting. – Replacement of SF 6 as protection gas by alternative inhibi- tors. – Development of investment castings with high mechanical properties. The metal reaction with the conventional shells containing colloidal silica (SiO 2 ) makes the use of these refractories im- possible when casting magnesium. [1] The basic exothermic reactions in Mg investment-castings when using colloidal sili- ca shells are described in (1), where Mg reacts with oxygen or silicon: [2–5] 2 Mg + O 2 → 2 MgO 2 Mg + SiO 2 → 2 MgO + Si 4 Mg + SiO 2 → 2 MgO + Mg 2 Si (1) RESEARCH NEWS ADVANCED ENGINEERING MATERIALS 2007, 9, No. 9 © 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 751 – [*] G. Arruebarrena, Dr. I. Hurtado Mondragon Gvi Eskola Politelenikoa University of Mondragon Mondragon, Spain Dr. J. Väinölä VTT Industrial Systems Espoo, Finland Dr. C. Cingi Helsinki University of Technology Helsinki, Finland S. Dévényi SpecialValimo Oy Espoo, Finland J. Townsend, S. Mahmood Stone Foundries Ltd. London, United Kingdom Dr. A. Wendt # , Dr. K. Weiss RWP GmbH Roetgen, Germany A. Ben-Dov Israel Aircraft Industries Ltd. Tel-Aviv, Israel # now with Center for Magnesium Technology Institute for Materials Research GKSS Forschungszentrum Geesthacht GmbH Geesthacht, Germany [**] This work was carried out in the frame of a STREP project (AST3-CT-2003-503826). G. A. and I. H. thank the Diputa- ción Foral de Gipuzkoa for the financial support. G. A. also acknowledges the Basque Government for providing her with a predoctoral fellowship. Investment casting offers high-quality castings with good dimensional accuracy, being therefore suit- able for aircraft applications. Since commercial ceramic shells react with Mg melts and appropriate in- hibitors being not available, magnesium alloys are not widely used in industrial investment-casting. In order to overcome this situation and enable the aircraft industry to take advantage of the light- weight properties of magnesium, the process is analyzed within the European FP6 IDEA project, which aims at developing new high-strength magnesium casting alloys for aeronautic applications.