AbstractThe following document describes the processing, testing and post-test analysis of two Be-Cu assemblies that have successfully met the heat load requirements for the first wall and dome sections for the International Thermonuclear Experimental Reactor (ITER) fusion reactor. Several different joint assemblies were evaluated in support of a manufacturing technology investigation aimed at diffusion bonding or brazing a beryllium armor tile to a copper alloy heat sink for fusion reactor applications. Judicious selection of materials and coatings for these assemblies was essential to eliminate or minimize interactions with the highly reactive beryllium armor material. A thin titanium layer was used as a diffusion barrier to isolate the copper heat sink from the beryllium armor. To reduce residual stresses produced by differences in the expansion coefficients between the beryllium and copper, a compliant layer of aluminum or aluminum-beryllium (AlBeMet-150) was used. Aluminum was chosen because it does not chemically react with, and exhibits limited solubility in, beryllium. Two bonding processes were used to produce the assemblies. The primary process was a diffusion bonding technique. In this case, undesirable metallurgical reactions were minimized by keeping the materials in a solid state throughout the fabrication cycle. The other process employed an aluminum-silicon layer as a brazing filler material. In both cases, a hot isostatic press (HIP) furnace was used in conjunction with vacuum-canned assemblies in order to minimize oxidation and provide sufficient pressure on the assemblies for full metal-to-metal contact and subsequent bonding. The two final assemblies were subjected to a suite of tests including: tensile tests and electron and optical metallography. Finally, high heat flux testing was conducted at the electron beam testing system (EBTS) at Sandia National Laboratories, NM. Here, test mockups were fabricated and subjected to normal heat loads to 10 MW/m2 (3 Hz) and abnormal heat loads to 250 MJ/m2 (0.5 s) to determine their performance under simulated fusion reactor conditions for first wall components. Both assemblies survived the normal heat loads with no visual damage. Optical and electron microscopy were used to evaluate the extent of the damage at the interfaces following the VDE simulations.
抄録 本稿では、国際熱核融合実験炉（ITER）の第一壁およびダイバータ部材の熱負荷要件を満たした2つのベリリウム-銅合金接合体の作製、試験、および試験後評価について述べる。拡散接合またはろう付けのいずれかによって、ベリリウム被覆材を銅合金ヒートシンクに接合した。接合プロセス中の有害な金属間化合物の形成を防止するため、ベリリウムと銅合金の間にチタン拡散バリア層を配置した。さらに、ベリリウムと銅合金間の熱膨張係数の差によって生じる熱応力を緩和するため、ベリリウムとチタンの間にアルミニウムまたはAlBeMet-150のコンプライアント層を配置した。拡散接合は熱間静水圧プレス（HIP）法を用いて実施し、ろう付けは真空雰囲気中で実施した。作製した接合体は、超音波検査、引張試験、および光学顕微鏡と電子顕微鏡によるミクロ組織観察によって評価した。さらに、サンディア国立研究所の電子ビーム試験装置（EBTS）を用いて、第一壁条件を模擬した定常熱負荷（最大10 MW/m²、3 Hz）および異常時熱負荷（最大250 MJ/m²、0.5秒）に対する熱疲労試験を実施した。両接合体とも定常熱負荷では視認可能な損傷は認められなかった。異常時熱負荷（垂直変位事象（VDE）模擬）後には、界面における損傷の程度を評価するために光学顕微鏡および電子顕微鏡観察を実施した。