ANALYSIS OF A BERYLLIUM-COPPER DIFFUSION JOINT AFTER HHF TEST

The development of beryllium-copper joints which can withstand relevan t ITER divertor conditions is one of the important tasks at the presen t time. One of the main problems associated with these joints is the i ntermetallic layers. The strength and life of these joints significant ly depend on the width and contents of the intermetallic layers. The o bjective of this work is to study the diffusion joint of TGP-56 beryll ium to OFHC copper after thermal response and thermocyclic rests with a beryllium-copper mock-up. The HHF test was performed on the e-beam f acility (EBTS, SNLA), The following methods were used for analysis: ro entgenographic analysis, X-ray spectrum analysis and fracture analysis . During the investigation the following studies were undertaken: the analysis of the diffusion boundary layer, which was obtained at the cr oss-section of one of the tiles, the analysis of the debonded surfaces of several beryllium tiles and corresponding copper parts and the ana lysis of the upper surface of one of the tiles after HHF tests. The jo int roentgenographic and element analyses revealed the following phase s in the diffusion zone: Cu2Be (similar to 170 mu m), CuBe (similar to 30 mu m), CuBe2 (similar to 1 mu m) and a solid solution of copper in beryllium. The phases Cu2Be, CuBe and the solid solution of copper in beryllium were detected by the quantitative microanalysis and the pha ses CuBe, CuBe2 and CuBe, by the roentgenographic analysis, The fractu re (origin) is located in the central part of the tiles. This crack wa s caused by residual stresses and thermal fatigue testing. This analys is provides important data on the joint quality and may be used for al l types of joints used for ITER applications.