High temperature residual strain measurements in a brazed sample for NET/ITER

The strain-free temperature in a brazed divertor mock-up for NET/ITER was measured using neutron diffraction. The investigated sample was a CuCrZr alloy cooling pipe armoured by a carbon/carbon fiber composite (CFC) monoblock tile. The joining between CFC and CuCrZr alloy was obtained by an intermediate layer of copper. Neutron diffraction measurements were carried out measuring the strain evolution as a function of temperature in the CuCrZr pipe and the lattice parameter of a reference powder of the same material, in the same temperature range. Both radial and tangential strains were determined inside the pipe in two representative points at 90°, finding well-reproducible results namely: radial strain vanishes at 370°C and tangential strain at 430°C approximately. These experimental results are discussed in the light of numerical analyses and simplified finite element method (FEM) calculations.