Y. Hiraoka, H. Hanado, T. Inoue, Okayama University of Science, Okayama, Japan; M. Naka, Osaka University, Osaka, Japan
W-19vol%Cu composite was brazed using a commercial Ag-Cu alloy (BAg-8 foil) with or without Ni-plating prior to brazing. Microstructure and chemical composition in and near the brazed layer were examined using SEM and/or EPMA. Joint strength of the brazement was evaluated using a three-point bend testing at room temperature. All the failed specimens were subjected to SEM observation and relation between the joint strength and the fracture mode was discussed.
Results are summarized as follows. 1) Without Ni-plating, the brazement demonstrated large scattering in joint strength. The average strength depended on the thickness of BAg-8 foil and was the highest at a thickness of 50μm. 2) With Ni-plating, the joint strengths were generally high and that demonstrated small scattering. 3) Without Ni-plating, a distinct relation between the joint strength and the fracture mode was recognized. The joint strength tended to increase with the decrease in area ratio of relative poor bonding. With Ni-plating, in contrast, the area of relative poor bonding was not observed and almost no relation between the joint strength and the fracture mode was recognized.
Summary: W-19vol%Cu composite was brazed using a commercial Ag-Cu alloy (BAg-8 foil) with or without Ni-plating prior to brazing. Microstructure and chemical composition in and near the brazed layer were examined using SEM and/or EPMA. Joint strength of the brazement was evaluated using a three-point bend testing at room temperature. All the failed specimens were subjected to SEM observation and relation between the joint strength and the fracture mode was discussed.
Results are summarized as follows. 1) Without Ni-plating, the brazement demonstrated large scattering in joint strength. The average strength depended on the thickness of BAg-8 foil and was the highest at a thickness of 50ƒÝm. 2) With Ni-plating, the joint strengths were generally high and that demonstrated small scattering. 3) Without Ni-plating, a distinct relation between the joint strength and the fracture mode was recognized. The joint strength tended to increase with the decrease in area ratio of relative poor bonding. With Ni-plating, in contrast, the area of relative poor bonding was not observed and almost no relation between the joint strength and the fracture mode was recognized.
