1. Some casting-products (casting)A simple casting technique

2. Microstructure: behind the desired Properties of the product materialPhasesGrainsvarious crystals structuresGrain boundary unit cellatomic bonding 3. Example:Ti Atomic number: 22 Phase: solid Crystal structure: Hexagonal Atomic radious: 140pm Electronic configuration: 1S22S22P63S23P63d24S2 Type: transitional metal Can be alloyed with: Fe (grain refinement) Al (grain refinement) Cu (hardening) 4. Structure of matter Atomic bonding: depending on electronic configurationAttractive forceForce between two atoms repulsive forcedeBonds: # Primary bonds: IonicCovalent#Second~ bonds: van der Waals forceMetallic 5. Metalliccovalent ionic 6. Dipole forceHydrogen bondingvan der Waals forces 7. Unit cellsCrystalline structureBCCFCC Allotropic characteristics?HCP 8. Imperfections in crystalsPoint defect point defect line defect surface defect 9. Line defect 10. Deformation in metallic crystal Elastic deformation Plastic deformation Plastic deformation mechanism: slip : slip, slip plane and slip direction twinning: twinning plane combination of both 11. Grain, grain size and grain boundary Grain: Individual crystals: array of repeating latticeGrain boundary: Growing crystals at random position and orientation interfere ultimately and form a surface defect at their interface. known as grain boundaryGrain size: Finer structure indicates in general higher strength. Larger grain boundaries ensures locking of the movement of dislocations in crystals under deformation, thus increasing strength of the material---- strain hardening 12. Engineering Materials Metals: Almost all have the crystalline structures: FCC, BCC, HCP are common Atoms are held together by metallic bonding. FCC metals are more deformable High electrical conductivity and thermal conductivityCeramics: Molecules are mostly characterised by both ionic and covalent bonding or in combination Strong attractive forces within the molecules. High hardness, electrically insulator, refractory, chemically inert Crystalline or noncrystalline structurePolymer: a large molecule (macromolecule) composed of repeating structural units connected by covalent chemical bonds. Molecules together in aggregate are weakly connected by secondary bonding Three types: thermoplastic, thermosetting plastic, elastomer