chapter 3 - C h a p t e r 3 / Structures of Metals and...

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C h a p t e r 3 / Structures of Metals and Ceramics C h a p t e r 3 Structures of Metals and Ceramics H igh velocity electron beams wavelike. wavelengths shorter than interatomic spacings, diffraction by atomic planes in crystalline materials, As x-rays
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C h a p t e r 3 / Structures of Metals and Ceramics Why Study Structures of Metals and Ceramics ? properties of some materials crystal structures directly related by For example: Magnesium(Mg) Beryllium(Be) Having same crystal structure more brittle than Gold(Au) Silver(Ag) Having same crystal structure Crystalline and Noncrystalline Different property having the same composition but different structure 3.1 INTRODUCTION
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C h a p t e r 3 / Structures of Metals and Ceramics Chapter 2 was concerned atomic bonding. the electron structure of the individual atoms. In this chapter next level of the structure of materials the arrangements of atoms in the solid state Introducing the concepts crystal and noncrystal For crystal structure unit cell crystallographic directions and planes metals and ceramics Single crystals and polycrystalline 非非非 非非 非非 非非非 非非非
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C h a p t e r 3 / Structures of Metals and Ceramics 3.2 Fundamental Concepts Crystalline. The state of a solid material characterized by a periodic and repeating three-dimensional array of atoms, ions, or molecules. long-range order the atoms will position themselves in a repetitive three- dimensional pattern, in which each atom is bonded to its nearest-neighbor atoms. All metals , many ceramic materials, and certain polymers form crystalline structures Materials crystalline Noncrystalline or amorphous No long-range atomic order 非非非非
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C h a p t e r 3 / Structures of Metals and Ceramics The description of crystalline atomic hard sphere model lattice Unit Cells 晶晶 3.3 Unit Cells hard sphere lattice unit cells 晶晶
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C h a p t e r 3 / Structures of Metals and Ceramics atomic hard sphere model : atoms (or ions) are thought of as being solid spheres having well-defined diameters. lattice . The regular geometrical arrangement of points in crystal space.(means a three-dimensional array of points coinciding with atom positions) unit cells : The basic structural unit of a crystal structure. It is generally defined in terms of atom (or ion) positions within a parallelepiped or prisms volume. the lattice parameters : The combination of unit cell edge lengths and interaxial angles that defines the unit cell geometry . a , b , c , and α , β , γ . 非非非非 非非 非非非非 非非非非非 非非
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C h a p t e r 3 / Structures of Metals and Ceramics Crystal structure. For crystalline materials, the manner in which atoms or ions are arrayed in space. It is defined in terms of the unit cell geometry and the atom positions within the unit cell.
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This note was uploaded on 10/11/2011 for the course ENG 210 taught by Professor Zhang during the Spring '10 term at Tianjin University.

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chapter 3 - C h a p t e r 3 / Structures of Metals and...

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