材料科学基础
Fundamental of Materials
Prof,Tian Min Bo
Tel,62795426, 62772851
E-mail,tmb@mail.tsinghua.edu.cn
Department of Material Science and Engineering
Tsinghua University,Beijing 100084
Lesson nineteen
§ 5.6 Dislocation in Motion
? Ⅰ.Edge dislocation
1,Slip (glide)
? Dislocation motion vs,atom movement.
? Direction,
? Plane:
? Dislocation motion vs,crystal movement.
vl ???
)( // vlbl ???? ??
v???? crystal movement (dislocation motion)
directs to the part of the crystal which
moves along,
vl ???
b?
v???? crystal movement
? ? ?? ?
? ? ?? ?
If the dislocation runs through the crystal from
one side to the other,the relative displacement of
the two parts of the crystal (on both sides of the
moving plane) is b.
2,Climb
① Dislocation moves along induced by diffusion.
②
③ Plane
④ Dislocation motion vs,crystal movement,
sn?
lv ???
vl ???
?
?
b?v?
positive climb 晶体合拢
negative climb 晶体分开
? Ⅱ.Screw dislocation
① only slip.
②
③ plane,
④ dislocation motion vs,crystal movement.
Macroscopic deformation =
Ad —— area over which dislocation swept.
As —— area of slip plane or climb plane.
lv ???
vl ???
bAA
s
d
b?
??
??
v?
? Ⅲ.Example:
given,
a dislocation loop on z plane with Burgers
Vector,,and the applied stress ( )
around the loop.
determine,
the possible movement of each segment of the loop
ABCD
b? ]010[ab ?? ij?
A
CB
D
x
y
z
0
zx?
yx?x?
zy?
y?
xy?
yz?
xz?
z?
b?
§ 5.7 Summary —— Properties of
Dislocation
1,Line imperfection.
2,It must be a continuous line running through the crystal or
a closed loop.
3,Its character can be described by and,
4,The physical meaning and the conservation of,
5,Rule governing the relation among,
bl ??
b?
vij ?? ?? ??
6,Dislocation density,
① Definition:
②,,,whisker
?
A
N
lll
Nl
V
l ????
321
11?
＝ NO,of dislocation emergence
?? sys V
vb
t
Sb
N
Sn
ll
bN
l
b
ll
lSn
l
u
ii
ii
i
?
?
?
??
?
?
?
?
??
?
??
?
?
?
?
?
?
323
21
1
3
x
z
y1l
3l
2l
Examples and Discussions
Exercise
Thank you !
19
Fundamental of Materials
Prof,Tian Min Bo
Tel,62795426, 62772851
E-mail,tmb@mail.tsinghua.edu.cn
Department of Material Science and Engineering
Tsinghua University,Beijing 100084
Lesson nineteen
§ 5.6 Dislocation in Motion
? Ⅰ.Edge dislocation
1,Slip (glide)
? Dislocation motion vs,atom movement.
? Direction,
? Plane:
? Dislocation motion vs,crystal movement.
vl ???
)( // vlbl ???? ??
v???? crystal movement (dislocation motion)
directs to the part of the crystal which
moves along,
vl ???
b?
v???? crystal movement
? ? ?? ?
? ? ?? ?
If the dislocation runs through the crystal from
one side to the other,the relative displacement of
the two parts of the crystal (on both sides of the
moving plane) is b.
2,Climb
① Dislocation moves along induced by diffusion.
②
③ Plane
④ Dislocation motion vs,crystal movement,
sn?
lv ???
vl ???
?
?
b?v?
positive climb 晶体合拢
negative climb 晶体分开
? Ⅱ.Screw dislocation
① only slip.
②
③ plane,
④ dislocation motion vs,crystal movement.
Macroscopic deformation =
Ad —— area over which dislocation swept.
As —— area of slip plane or climb plane.
lv ???
vl ???
bAA
s
d
b?
??
??
v?
? Ⅲ.Example:
given,
a dislocation loop on z plane with Burgers
Vector,,and the applied stress ( )
around the loop.
determine,
the possible movement of each segment of the loop
ABCD
b? ]010[ab ?? ij?
A
CB
D
x
y
z
0
zx?
yx?x?
zy?
y?
xy?
yz?
xz?
z?
b?
§ 5.7 Summary —— Properties of
Dislocation
1,Line imperfection.
2,It must be a continuous line running through the crystal or
a closed loop.
3,Its character can be described by and,
4,The physical meaning and the conservation of,
5,Rule governing the relation among,
bl ??
b?
vij ?? ?? ??
6,Dislocation density,
① Definition:
②,,,whisker
?
A
N
lll
Nl
V
l ????
321
11?
＝ NO,of dislocation emergence
?? sys V
vb
t
Sb
N
Sn
ll
bN
l
b
ll
lSn
l
u
ii
ii
i
?
?
?
??
?
?
?
?
??
?
??
?
?
?
?
?
?
323
21
1
3
x
z
y1l
3l
2l
Examples and Discussions
Exercise
Thank you !
19
