Abstract: There is disclosed a heat exchanger made of an aluminum alloy having a radiator part (10) and an oil cooler part (11) in combination and manufactured integrally by the brazing method, wherein a refrigerant tank (13) for covering and sealing the oil cooler part is made of an aluminum alloy, an aluminum alloy containing Si in an amount from more than 7.0 wt % to 12.0 wt %, Fe in an amount from more than 0.05 wt % to 0.5 wt %, Cu in an amount from more than 0.4 wt % to 8.0 wt %, Zn in an amount from more than 0.5 wt % to 10.0 wt %, and the balance of aluminum and inevitable impurities is used as a filler material of brazing sheets that are used for the oil cooler part and are brazed in the tank, and the refrigerant tank is assembled integrally with the radiator part and the oil cooler part by brazing with the brazing material.

Abstract: There is disclosed a heat exchanger made of an aluminum alloy having a radiator part (10) and an oil cooler part (11) in combination and manufactured integrally by the brazing method, wherein a refrigerant tank (13) for covering and sealing the oil cooler part is made of an aluminum alloy, an aluminum alloy containing Si in an amount from more than 7.0 wt % to 12.0 wt %, Fe in an amount from more than 0.05 wt % to 0.5 wt %, Cu in an amount from more than 0.4 wt % to 8.0 wt %, Zn in an amount from more than 0.5 wt % to 10.0 wt %, and the balance of aluminum and inevitable impurities is used as a filler material of brazing sheets that are used for the oil cooler part and are brazed in the tank, and the refrigerant tank is assembled integrally with the radiator part and the oil cooler part by brazing with the brazing material.

Abstract: According to the present invention, a first tube is constructed by connecting a plate material into a tubular shape. In the manufacturing process, after an inner fin is disposed around an outer wall of a second tube, the first tube is disposed around the second tube, and the first tube and the second tube are fixed by connecting the plate material in such a manner that the inner fin is in contact with the both tubes. In this way, the inner fin and both tubes are certainly contacted closely to each other without enlarging the second tube.

Abstract: There is disclosed an aluminum alloy tube whose outer surface is covered with a filler alloy by metal-spraying, wherein the base material of the tube has an uneven rough surface with the depth of 10 &mgr;m or more, and the difference between the highest projection of the base material surface and the highest projection of the filler alloy layer covering it is 3 to 25 &mgr;m; a heat exchanger, which is assembled by using the tubes; and a method of metal-spraying, which comprises metal-spraying an aluminum alloy filler powder in a melted state, by the high-velocity flame metal-spraying process, in which the filler contains 15 to 50% Si by weight, and the powder is mainly made up of particles whose diameter is 10 &mgr;m to 70 &mgr;m. The aluminum alloy tube is excellent in brazability and corrosion resistance, and by using the tube, it is possible to assemble a heat exchanger without allowing locally filler-unbonded parts to be formed.