5. 8 The Stress Around a Dislocation 1. Screw dislocation: Displacement:

Discrepancies between theory and practice in Deformation. 1. Morphology of the surface in deformation. 2. The great difference between theoretical and actual strength of single crystals (. >>)

Edge dislocation 1. Slip (glide) Dislocation motion vs. atom movement. Direction:l⊥讠 Plane:lb(l× Dislocation motion vs. crystal movement. → crystal movement→(dislocation motion)

1. Classification y Ideal or perfect crystal real or defect crystal According to dimension o point defect: vacancies, interstitial atoms s line defect dislocation planar defect: stacking fault o volume defect mosaic structure

4.9 Comparison Between Slip and Twinning Similar ity Both slip and twinning are shear process under shear stress T I. Differences 1. Orientation 2. Atom movement 3.y,△ a) Structure: Twinning is easy 4. Conditions b) Temperature da d c) Strain rate (c

4. Rule for elongation or reduction of R D All R.D. in the region where K1 and K2 makes an obtuse(acute) angle will increase (reduce) its length after twinning

1. The cause of rotation: Due to constraints, or boundary conditions imposed on the crystal. ll. The rule of rotation:

3. Application of Schmid's law How to determine the active S.S. for all the equivalent S.S. 2 Determine the active S.S. by Reflection Rule. Orientation cell for cubic crystals. Given: BCC Crystal having {110}slip system. Determine: active slip system in response to tensile loading along

1. Deformation process of polycrystalline materials Deformation process of industrial material consists of three stages Elastic. which is reversible

I Introduction Silicates are compounds that mainly composed of [sio4]. It is the essential components of most rock and soil, such as quartz, feldspar, mica etc