Engineering Materials - Crystal Errtricture.pptx

Engineering Materials - Crystal Errtricture

1. Engineering Materials Subject / Crystal Structure DR. ALTAYYEB KINHAR Shatt Al-Arab University College

2. 1 - Crystal structures Solid materials may be classified according to the regularity with which atoms or ions are arranged with respect to one another. 1 - A crystal line material is a material that the atoms are situated in a periodic array over large atomic distances. 2 - A non-crystal line or amorphous material is a material that does not have a long-range atomic order..

3. 1- Crystal structures

4. 2. Unit Cell Unit cell is the basic structural unit or building block of the crystal structure. The unit cell consists of lattice points that represent the locations of atoms or ions The entire structure then consists of this unit cell repeating in three dimensions, as shown

5. 2. Unit Cell

6. 2. Unit Cell 2.1. Cell Geometry

7. 2.2. Atomic Position Type Symbol Atomic Positions Simple -Cube SC Corners Only Body – Centred- Cube BCC Corners-Body Centre Face – Centred- Cube FCC Corners-Faces Centres Hexagonal close-packed HCP Corners - Centres

8. 2.2. Atomic Position Hexagonal close-packed HPC

9. 2.2. Atomic Position

10. 2.2. Atomic Position

11. The simple cubic unit cell is delineated by eight atoms, which mark the actual cube We should study the fellow: 1- Coordination Number : the number of closest neighbours to which an atom is bonded = number of touching atoms 2- No. of Atoms inside the unit cell 3- Relation Between (a) and (r) 4- Atomic Packing Factor (APF) 2.2. Crystal Structure 2.2.1. Simple cubic (SC)

12. The coordination number = 6 No. of Atoms inside the unit cell : Corner atoms are divided into 8 equal Number of atoms per unit cell = 1/8 x 8 (corners) = 1 شغل الفيديو 2.2. Crystal Structure 2.2.1. Simple cubic (SC)

13. BCC structure has a cubic unit cell with atoms located at each of the corners and a single atom at the cube centre. شغل الفيديو 2.2. Crystal Structure 2.2.1. Body- Centered Cubic (BCC)

14. The coordination number = 8 No. of Atoms inside the unit cell: Corner atoms are divided into 8 equal Number of atoms per unit cell = 1/8 x 8 + 1 = 2 2.2. Atomic Position 2.2.1. Body- Centered Cubic (BCC)

15. BCC FCC structure has a cubic geometry with atoms located at each of the corners and the centers of all the cube faces. Many metals have this FCC structure. شغل الفيديو 2.2. Crystal Structure 2.2.1. Face- Centered Cubic (FCC)

16. The coordination number = 12 4 corners + 8 faces = 2 NC No. of Atoms inside the unit cell: Corner atoms are divided into 8 equal Faces atoms divide to half cell = 1/8 x 8 corners = 1 = ½ x 6 (face) = 3 = 1 + 3 = 4 2.2. Atomic Position 2.2.1. Face- Centered Cubic (FCC)