HCP structures are generally:

HCP structures are generally:

• A. Higher Strength than BCC and more ductile than FCC
• B. Lower Strength than BCC and not as ductile as FCC but more than BCC
• C. Higher Strength than FCC and more ductile than BCC
• D. Lower Strength than FCC and less ductile than BCC

Answer: (D)

Focus on how crystal structure governs how easily a metal can deform. Plastic deformation relies on dislocations moving along slip systems. Hexagonal close-packed (HCP) structures have only a limited number of independent slip systems and more directional bonding, so dislocations move less freely, especially at room temperature. That restriction makes HCP metals relatively brittle and less ductile than metals with more slip systems. Among the common structures, FCC has the most slip systems and thus high ductility and plastic deformability. BCC sits in between and can be quite ductile, though its ductility is more temperature dependent. Because of the limited slip in HCP, these materials tend to be weaker in terms of yield strength compared with many FCC metals, and they are less ductile than BCC metals. Hence HCP structures are generally lower strength than FCC and less ductile than BCC.

Focus on how crystal structure governs how easily a metal can deform. Plastic deformation relies on dislocations moving along slip systems. Hexagonal close-packed (HCP) structures have only a limited number of independent slip systems and more directional bonding, so dislocations move less freely, especially at room temperature. That restriction makes HCP metals relatively brittle and less ductile than metals with more slip systems.

Among the common structures, FCC has the most slip systems and thus high ductility and plastic deformability. BCC sits in between and can be quite ductile, though its ductility is more temperature dependent. Because of the limited slip in HCP, these materials tend to be weaker in terms of yield strength compared with many FCC metals, and they are less ductile than BCC metals. Hence HCP structures are generally lower strength than FCC and less ductile than BCC.