Copper alloy-stainless steel bonded laminates for fusion reactor applications: tensile strength and microstructure

The tensile strength of copper alloy-stainless steel bi-layer panels joined by hot isostatic pressing or explosive bonding was tested over a temperatu re range 25-350 degreesC. The bonding processes caused changes in interfaci al microstructures which affected the interfacial mechanical properties. Ho t isostatic pressed materials studied included: precipitation strengthened CuNiBe or dispersion strengthened Cu-Al2O3 bonded to 316L stainless steel p lates and Cu-Al2O3 bonded to Cu-Al2O3. An explosive bonded panel of Cu-Al2O 3-316L stainless steel was also examined. Hot isostatic pressed panels show ed similar decreasing shear strengths with increasing temperature, while th e explosive bonded panel displayed substantially higher strength at 25 degr eesC but declined rapidly as the test temperature increased. Tensile streng ths of all panels were nominally lower than the constituent bulk material s trengths and delamination near the copper ahoy-stainless steel interface wa s the dominate failure mode in the bi-metallic panels. The joining processe s were found to alter the microstructure of the bond interfacial regions in the form of microporosity and Fe-Cr-B precipitate formation, NiBe precipit ate morphology changes and interdiffusion of constituent elements. (C) 2001 Elsevier Science B.V. All rights reserved.