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

2.7 Some Important Crystallographic Formulas 1. Zone and zone equation All Planes parellel to common axis [uvw] constitute a (crystal) zone, the [u v w] zone. If (h k l) belongs to zone [u v w], then hukv+=0 2.ifhuk+hw=0,then[uvw] lies in(hk) 3. For cubic crystals, [h (h k)

3. 1 Basic concepts of al loys 1. Definition An alloy is the combination of metal(s) with other elements through chemical bonding. Termino logy

1. Sing le crystal ver sus po l crystal 1. For single crystals there is only one type of structure with same orientation Single crystals is characterized by anisotropy 2. Polycrystal consists of a lot of grain, small single crystals, With same structure but different orientations. These small single crystals are called grains. The boundaries between them are called grain boundaries

Paulings three rules governing the structure of ionic compounds 1. Anion Coordination polyhedron rule Each cation is surrounded by an anion polyhedron, the distance between anion and cation is r=rt tr, while the cn depends on rt/r

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

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

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

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

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)