How can Gallium seemingly melt Aluminum?

Gallium is a solid metal at room temperature but melts at just 29.7℃ (85.5℉). when liquid gallium comes in contact with aluminum the two metals form a gallium aluminum alloy. As the gallium atoms penetrate the crystalline structure of aluminum the bonds in aluminum's lattice structure are greatly weakened. The resulting alloy is extremely fragile and brittle.