To improve joining strength by constituting a composite member from Cu-Ni- based alloy whose surface layer part contains a specific quantity of Ni.
A composite member 1 consists of a member main body 2 made of a light alloy and a material 3 to be cast-in, which has been joined in the casting process of the member main body 2 made of the light alloy. As the material 3 to be cast-in, a Cu-Ni-based alloy having a surface layer part 4 whose Ni content has been set to 10 wt.%≤Ni≤90 wt.%, is used. The surface layer part 4 has a good wettability to molten metal made of light alloy, and has a satisfactory diffusion property to the molten metal. Further the Cu-Ni-based alloy constituting the surface layer part 4 is a complete solid solution. Since it has specific compositions, it has high strength, and the joining strength of the member main body 2 made of the light alloy and the material 3 to be cast-in is improved. Preferably the material 3 to be cast-in consists of a surface layer 6 which is one body with a main body 5 made of a Fe-based alloy, and the surface layer 6 is a Cu-Ni-based alloy by a heat treatment in the reduced atmosphere of an Ni layer and a Cu layer laminated successively on the main body 5.
HATA TSUNEHISA
ITO TAKEO
NAGASE TOSHIYA
SHIMIZU HIDEO
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