Preliminary Evaluation of Beryllium and Copper Joints by Heat Load Tests

X. Liu (Sp), J. Chen, F. Zhang, Z. Xu, N. Zhang, C. Pan, Y. Liu, Southwestern Institute of Physics, Sichuan (China); Y. Yu, Nuclear Power Institute of China, Chengdu , Sichuan (China); Z. Wang, L. Wang, Ninggxia Orient Non-ferrous Metals Group Co. Ltd, Ningxia, Shizuishan City (China); P. Zhang, Chinese Academy of Engineering Physic, Mianyang City, Sichuan (China) 
Research and development of the FW mock-ups of ITER have being carried out in Southwestern Institute of Physics (SWIP) by the cooperation with domestic institutes and companies related to beryllium production and handling. Be/Cu joints with Al (AlSiMg alloy) and Ti interlayer have been prepared by hot isostatic press (HIP). The main parameters of HIP are 823-893 K in temperature, 80-100 MPa in pressure and 2 hours in holding time for the former while 1073-1123 K in temperature, 120 MPa in pressure and 2 hours in holding time for the latter. Both metal foils and PVD (physical vapor deposition) coating of Al and Ti as the interlayer between beryllium and CuCrZr alloy were adopted. Be/Cu joints were annealed at 573 K for several hours after HIP bonding. Metallurgical observation revealed that some intermetallic layers formed at the interface in the case of Be/Cu joints with Ti interlayer and no such intermetallic phases formed for Be/Cu joints with Al (AlSiMg) as interlayer. Tensile strength of Be/Cu (Ti) joints is much higher than Be/Cu (Al) joints and some Be/Cu (Ti) joints have tensile strength of over 100 MPa.
Heat load tests were performed in an electron beam facility with Gaussian energy distribution. The maximum power of the electron beam was 3 kW and maximum irradiation area was 20 mm in diameter. The size of Be/Cu joints for heat load tests is 20X20X32 mm3 with a hole of 10 mm diameter in Cu blocks for actively cooling. Cyclic heat loading indicated Be/Cu (Ti) superior to Be/Cu (Al) and some Be/Cu (Ti) specimens can sustain 1000 cycles at 4 MW/m2 heat flux. A reason for low cyclic heat load resistance probabilities of Be/Cu (Al) joints could be due to relatively low pressure of HIP bonding. Further investigation is under way.

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