I/We Claim:
[Claim 1]
A method for bonding dissimilar metals to each other, the method comprising:
a dissimilar metal layer forming step of supplying a mixed filler material, including a filler material formed of a first metal and particles formed of a second metal having a higher melting point than the first metal, to a surface of a first material to be bonded that is formed of the first metal, and heating the mixed filler material to a temperature equal to or higher than a melting point of the first metal and equal to or lower than a melting point of the second metal, to form a dissimilar metal layer;
a second metal layer forming step of supplying a filler material formed of the second metal to a surface of the dissimilar metal layer, and heating the filler material formed of the second metal to a temperature equal to or higher than the melting point of the second metal, to form a second metal layer formed of the second metal; and
a second material-to-be-bonded welding step of welding a second material to be bonded, which is formed of the second metal, to the second metal layer. [Claim 2]

The method for bonding dissimilar metals to each other according to Claim 1,
wherein a dissimilar metal laminated layer structure in which a plurality of the dissimilar metal layers are sequentially laminated is formed by repeating the dissimilar metal layer forming step,
wherein execution is made such that a proportion of the first metal in the mixed filler material to be used in a first dissimilar metal layer forming step of a laminating sequence is larger than a proportion of the second metal, and
wherein second and subsequent dissimilar metal layer forming steps of the laminating sequence are executed such that, as the laminating sequence increases, the proportion of the second metal becomes sequentially larger and the proportion of the first metal becomes sequentially smaller. [Claim 3]
The method for bonding dissimilar metals to each other according to Claim 1 or 2,
wherein a dissimilar metal laminated layer structure in which a plurality of the dissimilar metal layers are sequentially laminated is formed by repeating the dissimilar metal layer forming step, and
wherein the plurality of dissimilar metal layer forming steps are executed such that a particle diameter

of each of particles of the second metal becomes sequentially smaller as the laminating sequence increases. [Claim 4]
The method for bonding dissimilar metals to each other according to any one of Claims 1 to 3,
wherein a dissimilar metal laminated layer structure in which a plurality of the dissimilar metal layers are sequentially laminated is formed by repeating the dissimilar metal layer forming step, and
wherein the plurality of dissimilar metal layer forming steps are executed such that a heating temperature of the mixed filler material becomes higher as the laminating sequence increases. [Claim 5]
The method for bonding dissimilar metals to each other according to any one of Claims 1 to 4,
wherein the filler material formed of the first metal is a wire.