What type of crystal structure do brittle metals, like titanium, often possess?

Brittle metals such as titanium often exhibit a hexagonal close-packed (HCP) crystal structure. This structure is characterized by a dense arrangement of atoms, where each atom is surrounded by twelve neighboring atoms, maximizing the packing efficiency. The HCP arrangement contributes to the mechanical properties of the metal, including its strength and brittleness.

In titanium's case, this crystal structure plays a significant role in its performance at various temperatures; at lower temperatures, it tends to be relatively brittle, which is a common characteristic of materials with a hexagonal close-packed structure.

This contrasts with the other crystal structures listed. For instance, the cubic face-centered arrangement typically leads to materials that are more ductile and tough, while body-centered cubic structures can also be associated with ductility but may have different properties under specific conditions. An amorphous structure, lacking a long-range order, generally does not apply to crystalline metals like titanium, further confirming that the hexagonal close-packed structure is the most appropriate classification for titanium as a brittle metal.