文档介绍：psi是一种压力单位,定义为英镑/平方英寸,145psi=1Mpa
PSI英文全称为Pounds per square inch。P是磅pound,S是平方square,I是英寸inch。把所有的单位换成公制单位就可以算出:1bar≈
1 KSI = 1000 lb / = 1000 x x N / ( mm)2 = N / mm2
材料机械强度性能单位,要用到试验机来检测
Density of Slip Planes
 
The planar density of the (112) plane in BCC iron is atoms/cm2. Calculate the planar density of the (110) plane and the interplanar spacings for both the (112) and the (110) planes. On which type of plane would slip normally occur?
 
(112) planar density:
 
The point of this problem is that slip generally occurs in high density directions and on high density planes. The high density directions are directions in which the Burgers' vector is short, and the high density planes are the "smoothest" for slip.
 
It will help to visualize these two planes as we calculate the atom density.
 
 
The (110) plane passes through the atom on the lattice point in the center of the unit cell. The plane is rectangular, with a height equal to the lattice parameter a0 and a width equal to the diagonal of the cube face, which is Ö2 a0.
Lattice parameter (height):
 
Width:
 
Thus, according to the geometry, the area of a (110) plane would be
 
There are two atoms in this area. We can determine that by counting the piece of atoms that lie within the circle (1 for the atom in the middle and 4 times 1/4 for the corners), or using atom coordinates as discussed in Chapter 3. Then the planar density is
 
The interplanar spacing for the (110) planes is
 
For the (112) plane, the planar density is not quite so easy to determine. Let us draw a larger array of four unit cells, showing the plane and the atoms it passes through.
 
 
This plane is also rectangular, with a base width of Ö2 a0 (the diagonal of a cube face), and a height of Ö3 a0 (the body diagonal of a cube). It has four atoms at corners, which are counted as 1/4 for the portion inside the rectangle (4 x 1/4) and two atoms on the edges, counted as 1/2 for th