85.6 Dis location in Mot ion 从 It stress stress A H Unit step K. Chen
§5.6 Dislocation in Motion
◆|. Edge dislocate i on 1. Slip(glide) Dislocation motion vs atom movement Direction:l⊥ Plane:l×b(1×w Dislocation motion vs, crystal movement. z→ crystal movement→v( dislocation motion
◆ Ⅰ.Edge dislocation 1. Slip (glide) ◆ Dislocation motion vs. atom movement. ◆ Direction: ◆ Plane: ◆ Dislocation motion vs. crystal movement. l v ⊥ l b (// l v) v crystal movement (dislocation motion)
I xv directs to the part of the crystal which moves along b τ→ crystal movement→v Q33 Ship plane Q Stip plure Direction of dis/ocation movement
directs to the part of the crystal which moves along . l v 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
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 D Dislocation moves along n induced by diffusion Plane I×v a Dislocation motion VS crystal movement
2. Climb ① Dislocation moves along induced by diffusion. ② ③ Plane ④ Dislocation motion vs. crystal movement. ns v l ⊥ l v ⊥ ⊥ b v
positive climb晶体合拢 negative climb晶体分开
positive climb 晶体合拢 negative climb 晶体分开
I. screw dislocation ① only slip ②2p⊥l 3pane:l× E B (4 dislocation motion VS. crystal movement Macroscopic deformation =-6 Ad- area over which dislocation swept A5-area of slip plane or climb plane
◆ 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. v l ⊥ l v b A A s d b v
Examp le: gIven. a dislocation loop ABCD on z plane with Burgers Vector b, b=a[0101, and the applied stress(i) around the loop determine. the possible movement of each segment of the loop
◆ 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 b = a[010] ij
∠ A D B
A B C D x y z 0 zx yx x zy y xy yz xz z b
