Yamaguchi Tomiko

Formation of Intermetallic Compounds on the Bond Interface of Aluminum-Clad Copper and its Influence on Bond Tensile Strength

Production of aluminium-clad copper has been performed using vacuum roll bonding, hundreds nm of intermetallic compounds are formed on the bond interface. On the tensile testing, it is broken from the base metal of aluminium and high bond tensile strength is available. In this study, heat treatment has been taken to aluminium-clad copper produced by vacuum roll bonding. Microstructure observation, EPMA, EDS and XRD have been carried to the investigation of the formation of intermetallic compounds. As a result, 3 types of intermetallic compounds such as CuAl2, CuAl and Cu9Al4 were formed at the bond interface of aluminium-clad copper. And it was clarified that the apparent activation energy for growth behavior of CuAl and Cu9Al4 is lower than CuAl2. The effect of intermetallic phases on bond strength has also been investigated with the growth of intermetallic compounds. The decrease of tensile strength has been clarified. The broken position is near the interface between CuAl2 and CuAl. Furthermore, the bond strength of aluminum-clad copper is seriously affected by the thickness of CuAl2.

Computational fluid dynamics analysis of shielding gas behaviour in tungsten inert gas welding of titanium plate

To minimize the volume of argon required for on-site TIG welding of titanium plate, we investigated the behaviour of argon flow in a trailing-shielding box by means of computational fluid dynamics (CFD) simulations. In this study, we designed a model of a solid rectangular shielding box consisting of 9.5 × 105 tetrahedral elements. Then, argon flow was simulated for various shielding parameters, namely the gap between the box and floor and the argon supply rate. In an experiment using dry ice mist to visualize the flow of argon, we investigated the flow from a shielding box model consisting of acrylic plates for various shielding parameters. In this manner, we studied the relation between the oxygen content in the shielding box and the shielding parameters. Then, a conventional shielding box and a prototype shielding box were evaluated experimentally. We confirmed the relation between the oxygen content in the shielding boxes and the degree of oxidation on the bead surface in TIG arc melt-run welding of titanium plate. The experimental results show that the simulation model used in the CFD simulations allowed the behaviour of argon to be predicted. We conclude that the simulation model is useful for improving the structure of the shielding box.