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REVIEW MATERIALS SCIENCE

REVIEW MATERIALS SCIENCE. Chap. 3 UNIT CELL. CRYSTAL STRUCTURES. FCC (FACE – CENTERED CUBIC). SC (SIMPLE CUBIC). HCP (HEXAGONAL CLOSE PACKED). BCC (BODY – CENTERED CUBIC). DIFFERENT POSSIBLE COMBINATIONS OF LATTICE PARAMETERS. CRISTALOGRAPHIC DIRECTIONS. CRISTALOGRAPHIC PLANES.

aphrodite-charles
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REVIEW MATERIALS SCIENCE

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  1. REVIEW MATERIALS SCIENCE Chap. 3UNIT CELL

  2. CRYSTAL STRUCTURES FCC (FACE – CENTERED CUBIC) SC (SIMPLE CUBIC) HCP (HEXAGONAL CLOSE PACKED) • BCC (BODY – CENTERED CUBIC)

  3. DIFFERENT POSSIBLE COMBINATIONS OF LATTICE PARAMETERS

  4. CRISTALOGRAPHIC DIRECTIONS CRISTALOGRAPHIC PLANES

  5. EXERCICE 3.31 y 3.41 • Here are unit cells for two hypothetical metals: • What are the indices for the directions indicated by the vectors in the sketch (A, B)? • What are the indices for the two planes drawn in sketch ?

  6. CRYSTALLINE MATERIALS SINGLE CRYSTALS POLYCRYSTALLINE MATERIALS

  7. CHAP. 4 IMPERFECTIONS IN SOLIDS POINT DEFECTS • Vacancies: -vacant atomic sites in a structure. • Self-Interstitials: -"extra" atoms positioned between atomic sites.

  8. POINT DEFECTS IN ALLOYS Two outcomes if impurity (B) added to host (A): • Solid solution of B in A (i.e., random dist. of point defects) OR Substitutional alloy (e.g., Cu in Ni) Interstitial alloy (e.g., C in Fe) • Solid solution of B in A plus particles of a new phase (usually for a larger amount of B) Second phase particle --different composition --often different structure.

  9. LINE DEFECTS INCREMENTAL SLIP • Dislocations slip planes incrementally... • The dislocation line (the moving red dot)... ...separates slipped material on the left from unslipped material on the right. Atomic view of edge dislocation motion from left to right as a crystal is sheared.

  10. Metal Ingot Schematic ~ 8cm AREA DEFECTS: GRAIN BOUNDARIES Grain boundaries: • are boundaries between crystals. • are produced by the solidification process, for example. • have a change in crystal orientation across them. • impede dislocation motion.

  11. OPTICAL MICROSCOPY Grain boundaries... • are imperfections, • are more susceptible to etching, • may be revealed as dark lines, • change direction in a polycrystal.

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