GATE2018-1-17

Question

The number of atoms per unit cell and the number of slip systems, respectively, for a face-centered cubic (FCC) crystal are

• A. $3, 3$
• B. $3, 12$
• C. $4, 12$
• D. $4, 48$

Answer 1

Option C

No of atoms on corners: 1/8*8 = 1

No of atoms on faces: 1/2*6 = 3

The number of atoms in FCC unit cell is the sum of no of atoms on corners and faces i.e., 1+3 = 4.

A slip system is composed of a slip plane and a slip direction. It occurs along the close-packed plane. Therefore, in FCC crystal, the number of slip systems is 12