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In the present study, friction welding of tube to tube plate using an external tool (FWTPET) was used to weld copper tubes with aluminum plates. Tubes were prepared with holes along the faying surfaces of tubes and cleaned before welding. The weld microstructure shows line of stir zone (SZ), a narrow thermo mechanically affected zone and heat affected zone (HAZ). The welded samples were found to have satisfactory joint strength and the XRD study showed the presence of AlCu intermetallic in the weld zone. The hardness survey revealed that there was a slight increase in hardness adjacent to the weld interface due to grain refinement. Better weld joints were achieved when the tool rotation speed and interference are 1500 rpm and 0.8 mm respectively. The present study confirms that a high quality copper tube to aluminium tube plate joint can be achieved by FWPET process.

In the present study, diffusion bonding of Cu/Cu was carried out at 750 °C for 60min under uniaxial pressureof 5-15MPa in vacuum. The joints were evaluated by Microtensile testing and Ultrasonic testing. The bond qualities were assessed by destructive testing (strength ratio) and nondestructive ultrasonic C–scan testing method.The bond quality obtained by both the methods is correlated in a view to use the C scan for regular testing. The optimum condition for obtaining the best bonding characteristics is reported. The joint obtained by diffusion bonding at 750 °C and a applied pressure of 15MPa for 60min gives the best bonding characteristics.Keywords: diffusion bonding/welding, Interface, Ultrasonic nondestructive testing.

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