Why do copper and titanium improve zinc roofing alloys?

Copper and titanium are added to zinc roofing alloys to significantly enhance their mechanical performance, particularly their creep strength—the material's resistance to permanent deformation under continuous stress.12

When these alloys are rolled, the titanium and zinc particles align in the direction of the rolling, forming "stringers." These stringers serve as the primary strengthening feature of the alloy by restricting grain movement. Furthermore, because these alloys possess a fine grain size, they exhibit excellent ductility at both normal and low temperatures. This makes the material highly suitable for various sheet-forming processes, such as bending, stamping, cutting, and stretching, which are essential for building applications like roof cladding, gutters, and flashing.1