Abstract: A metal member-welded structure includes: a Cu member; an Al member; and a welded portion formed by melting and solidifying each of materials of the Cu member and the Al member. The Cu member includes a Cu-based material containing Cu as a main component. The Al member includes an Al-based material containing Al as a main component and a plating layer that covers a side of the Al-based material, the side being close to a surface of the Cu member. The welded portion includes a sea-island structure in a vicinity of the surface of the Cu member. The sea-island structure includes: a plurality of island portions containing pure Al, and a sea portion interposed among the island portions. The sea portion has a eutectic structure having: a phase of an intermetallic compound of Cu and Al; and a phase of pure Al.

Abstract: A metal member-welded structure includes: a Cu member; an Al member; and a welded portion formed by melting and solidifying each of materials of the Cu member and the Al member. The Cu member includes a Cu-based material containing Cu as a main component. The Al member includes an Al-based material containing Al as a main component and a plating layer that covers a side of the Al-based material, the side being close to a surface of the Cu member. The welded portion includes a sea-island structure in a vicinity of the surface of the Cu member. The sea-island structure includes: a plurality of island portions containing pure Al, and a sea portion interposed among the island portions. The sea portion has a eutectic structure having: a phase of an intermetallic compound of Cu and Al; and a phase of pure Al.

Abstract: A method of manufacturing a metal member-welded structure includes: a preparing step of preparing an Al alloy member formed of an Al-based alloy and a Cu member containing Cu as a main component; and a welding step of applying laser from a side of the Al alloy member to the Al alloy member and the Cu member disposed to face each other, and welding the Al alloy member and the Cu member to each other. The Al-based alloy contains, as an additional element, one of: 1 mass % or more and 17 mass % or less of Si; 0.05 mass % or more and 2.5 mass % or less of Fe; and 0.05 mass % or more and 2.5 mass % or less of Mn. A laser applying condition satisfies an output of 550 W or more and a scanning rate of 10 min/sec or more.