DEVELOPMENT OF AL-GE BASE RHEOCAST BRAZING ALLOYS

This study concerns the development of an aluminium-germanium rheocast brazing alloy able to join replaceable sacrificial protections onto p ermanently cooled substrates in the ITER divertor. The rheocast alloy must be solid at the in-service temperature (up to 350 degrees C) and semi-solid, with a viscosity close to that of grease, in a wide range of temperature above: this last property will allow the in-situ replac ement of the sacrificial components even on vertical surfaces. This pa per describes the fabrication route of the rheocast and reports the me chanical characterisation both up to 400 degrees C and in the semi-sol id region. Moreover, the brazing process has been optimized to obtain sound joints. The structure, mechanical resistance and thermal stabili ty of the Al-Ge/Cu joint are presented. Successive brazing tests have been performed to show the feasibility of sacrificial parts removal an d replacement.