Compared to BCC metals, FCC metals generally have which properties?

Compared to BCC metals, FCC metals generally have which properties?

• A. Higher Strength and Lower Ductility
• B. Lower Strength and Higher Ductility
• C. Higher Strength and Higher Ductility
• D. Lower Strength and Lower Ductility

Answer: (A)

Dislocation movement on multiple slip systems governs how ductile a metal can be. FCC metals have 12 slip systems on close-packed planes, so dislocations glide readily in many directions, giving them high ductility. BCC metals, especially at room temperature, have fewer slip systems that are easily activated and a higher resistance to dislocation motion, which tends to increase strength while reducing ductility. Therefore, in general, FCC metals exhibit lower strength and higher ductility compared with BCC metals. The idea that FCC metals are stronger and less ductile contradicts this common trend.

Dislocation movement on multiple slip systems governs how ductile a metal can be. FCC metals have 12 slip systems on close-packed planes, so dislocations glide readily in many directions, giving them high ductility. BCC metals, especially at room temperature, have fewer slip systems that are easily activated and a higher resistance to dislocation motion, which tends to increase strength while reducing ductility. Therefore, in general, FCC metals exhibit lower strength and higher ductility compared with BCC metals. The idea that FCC metals are stronger and less ductile contradicts this common trend.