Which of the following is not a characteristic of ductility in metals?

Ductility in metals refers to their ability to deform under tensile stress, allowing them to be stretched into wires or sheets without breaking. A key characteristic of ductile materials is their capability to experience significant elongation while still maintaining structural integrity.

The ability to stretch without breaking and the ability to be drawn into wires are fundamental properties of ductility. These attributes highlight how ductile materials can undergo substantial deformation when subjected to tensile forces. Additionally, the ability to deform permanently aligns with the definition of ductility, as ductile materials can sustain non-reversible changes in shape.

In contrast, the ability to withstand heavy loads is not a defining characteristic of ductility. While some ductile materials can support heavy loads, this aspect is more related to the material's strength and overall structural integrity rather than its ductility. Therefore, this choice stands out as not being a characteristic of ductility, focusing instead on load-bearing capacity, which pertains to different mechanical properties.