J. P. Bergmann, D. J. Wilden, Technische Universität Ilmenau, Ilmenau, Germany

Summary: Diffusion bonding is an attractive joining technology for advanced materials, especially when conventional fusion welding processes degrade the properties of the materials in the heat affected zone and in the melt pool. In general diffusion bonding is performed at relatively high temperature of about 0,5-0,8 melting temperature. The increased interest in light weight concepts leads to set in a component contemporarily different light weight metals, which have to be joined to each other. Beyond arc- and laser welding technologies, which are nowadays usual in the high mass rate production, diffusion welding offers the unique possibility to join different metals avoiding large brittle intermetallic phases, which form generally in the melt pool while cooling. The artifice is to perform diffusion joining, so that for example aluminium can be dissolved in the -Ti crystal, which occurs for temperatures below 550°C at about 10 at.-%, without forming brittle intermetallics. In the present paper experimental results of diffusion bonding of titanium/aluminium joints will be presented. First investigations were performed on Al99,5 and cp-Ti, in order to understand the diffusion process for technical pure materials. In further investigations AA5xxx and AA6xxx are joined with cp-titanium (T<550°C), in order to evidence the effect of alloying elements. The joints are evaluated by optical as well as SE-microscopy. EDX-analysis allows the qualitative definition of the diffusion zone as well as the composition. The dimensions of the diffusion zone are then plotted in relation to time and temperature, so that a technical diffusion coefficient can be defined. Selected results upon mechanical behaviour of joints will be reported too, and confirm the suitability of the process for high strength applications.