Use of refractory alloys in NET divertor design and comparative study of mechanical properties after enduring disruptive heat loads or brazing and ageing treatment

For the control of the plasma composition and for the extraction of power and helium ash, a poloidal divertor configuration is being considered for the present NET study. Refractory metal alloys may be used as tile as well as heat sink material. Under a contract awarded by the NET Team, Cime Bocuze (F) performed a limited comparative study of ten refractory metals and alloys. Tensile tests up to 8000C were performed on sintered Mo, wrought Mo, Z6 (Mo-ZrO2), TZM, Mo-5 Re, Mo-41 Re, sintered W, wrought W, W-5 Re and W-26 Re, in delivery state and after ageing 10 days at 6000C; the 10 days ageing, simulating the integrated divertor life time. Slow bend tests were done from room temperature to respectively 8000C and 6000C on refractory metal samples, previously brazed to graphite or to copper. Finally impact tests till 8000C were carried out on samples being disposed to high energy flux deposition of 3 or 15MJ/mm2 by laser; this, to simulate the energy deposition that might occur on the material during a plasma disruption. 14 refs., 9 tabs., 11 figs. (Author)