# (materials science) slip system

by asdf1
Tags: materials, science, slip
 P: 736 for the FCC cubic, there are 12 slip systems: 4 {111} planes and 3 <110> directions... what i don't understand is why are there 4{111} planes instead of 1?
 Admin P: 21,865 How many corners to a cube? How many major diagonals?
Emeritus
PF Gold
P: 11,155
 Quote by asdf1 what i don't understand is why are there 4{111} planes instead of 1?
In a cube, you'll find you can draw 8 {1,1,1} planes. However, you'll also see that only 4 of these are unique - the other 4 being parallel to these and separated from them by distance of a/sqrt(3), where 'a' is the cube edge.

What I don't understand is why there are only 3 <110> directions when it looks to me like there should be 6 (2 face diagonals on each of the 3 faces).

 Admin P: 21,865 (materials science) slip system Rotational symmetry - rotate the cube 90° about the normal to the face plane, and one face diagonal transforms to the other (perpendicular) diagonal. Or rotate the cube 180° about the normal to the base and the <110> becomes <1$\bar1$0>.
 P: 736 ok~ thank you!
Emeritus
 Quote by Astronuc Rotational symmetry - rotate the cube 90° about the normal to the face plane, and one face diagonal transforms to the other (perpendicular) diagonal. Or rotate the cube 180° about the normal to the base and the <110> becomes <1$\bar1$0>.