Niobium as mint metal: Production–properties–processing

For application as coin metal the used materials must be able to meet the demands in a wide range. This paper describes the selection criteria for coin metals and gives an overview about the quality and production requirements needed for special collector coins. Niobium was selected as core metal for a special 25 Euro bi-metallic coin collectors series issued by the Austrian Mint. As counterpart Silver is used as surrounding metal.A special feature of this bi-metallic coin is the use of coloured niobium inserts. The combination of these materials with distinctly different material properties, especially the deformation behaviour, and the use of the coloured niobium insert makes an adaptation of production parameters and manufacturing philosophy necessary. Beside a general overview about the properties and applications of niobium the paper describes the experience gathered during production of the bi-metallic coins.