Why can copper be stretched into wire without breaking?

Copper can be stretched into wire without breaking because it is an extremely ductile metal. This property is fundamentally linked to its face-centred cubic crystal structure and the nature of the metallic bond.1234

In a metallic structure, the valence electrons are nonlocalized, meaning they move freely throughout the crystal rather than being associated with specific atoms. This creates a nondirectional binding force between the metal ions. When copper is drawn into wire, its ions can be easily displaced relative to one another without fracturing the material. The mobile, nonlocalized electrons act as a buffer between the positively charged ions, preventing them from repelling each other and causing the crystal to break.4