Activities of HIP joining of plasma-facing armors in the blanket first-wall in Korea

• Published in: Fusion engineering and design 2016-11, Vol.109-111, p.448-453
• Main Authors: Jung, Yang-Il, Park, Jeong-Yong, Choi, Byoung-Kwon, Lee, Jung-Suk, Kim, Hyun-Gil, Park, Dong-Jun, Park, Jung-Hwan, Kim, Suk-Kwon, Lee, Dong-Won, Cho, Seungyon
• Format: Article
• Language: English
• Subjects: Beryllium; Blanket armor; First-wall fabrication; Hot isostatic pressing; Tungsten
• ISSN: 0920-3796; 1873-7196
• DOI: 10.1016/j.fusengdes.2016.02.083

•HIP joints of Be/CuCrZr, Be/FMS, W/FMS were demonstrated.•The process conditions for HIP joining were developed.•For the joining of Be, coating interlayers as well as thick diffusion barrier was developed.•For the joining of W, double-staged HIP was applied for the joint integrity.•No significant defects nor a brittle failure were observed along the joint interface. Joining technology for dissimilar materials was developed for the fabrication of an ITER blanket first-wall, which consisted of Be, CuCrZr, and stainless steel (SS). The Be/CuCrZr/SS joint was fabricated using a hot isostatic pressing (HIP) method. Beryllium armor was joined to the CuCrZr/SS block at 580°C under 100MPa. The optimal interlayer coatings of Cr/Cu and Ti/Cr/Cu were developed using an ion-beam assisted physical vapor deposition. Beryllium is also a candidate armor material for the TBM first-wall. Successful joining of Be to ferritic-martensitic steel (FMS) was accomplished using an HIP method by introducing the thick diffusion barrier. A thick diffusion barrier of a Cu foil(10μm) limited the excessive diffusion and prevented the formation of brittle phases at the Be/FMS interface. Be and FMS were bonded at 650–850°C; however, a temperature of lower than 750°C was recommended to avoid material degradation of FMS. In addition, the joining of W to FMS has been developed. Tungsten is another armor material applicable to more severe plasma conditions. The large difference in the thermal expansion between W and FMS was resolved by introducing the Ti interlayer and Mo separator. Moreover, the double-staged HIP (the first stage at 900°C and 100MPa and the second stage at 750°C and 70MPa) was applied to suppress the edge delamination of W/FMS joints during thermal history.