Interface formation and strength of Be/DSCu diffusion bonding

Beryllium has been proposed to be used as a plasma facing material of the f irst wall for ITER, and will be bonded by HIP process to Dispersion Strengt hened Copper (DSCu). Be/DSCu diffusion bonding tests in the range of temper ature from 600 degrees C to 850 degrees C by hot pressing techniques have b een conducted to identify the effect of bonding temperature and time on int erface formation and joint strength. The bonded Be/DSCu joints were evaluat ed by microstructural analysis of the interface and shear strength tests at room temperature. The diffusion layer of directly bonded Be/DSCu joints an d the joints with Be-Cu interlayer consisted of Be2Cu(delta) phase on the B e side and Cu + BeCu(gamma) phase on the DSCu side. Cu + BeCu(gamma) phase generated remarkably fast at 800-850 degrees C. The thickness of the diffus ion layer was linear to a square root of bonding time. Shear strength of th e joints bonded at 650-750 degrees C are all around 200 MPa. Shear strength is dominated by the formation of the layer of Be2Cu(delta) phase on the Be side. (C) 1998 Published by Elsevier Science B.V. All rights reserved.