材料科学基础 08PPT课件.ppt

材料科学基础_08PPT课件材料科学基础Fundamental of Materials
Prof: Tian Min Bo
Tel: 62795426 ,62772851
E-mail: ******@.
Department of Material Science and Engineering
Tsinghua University. Beijing 100084
Lesson eight
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Chapter Ⅲ
The Structures of Alloys
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§ Basic concepts of alloys
Ⅰ.Definition
An alloy is bination of metal(s) with other elements through chemical bonding.
Ⅱ.Terminology
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1. Component (or constituent)
ponent system
ponent system binary system
ponent system ternary system
ponent system quarternary system
ponent system quinary system
ponent system
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2. Composition
It can be expressed either by atomic percentage (mol fraction) Xa or by mass percentage Xm
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3. Phase
A phase is a homogeneous part of the material in which no abrupt change position, structure and properties occurs.
An alloy may be single phase or multi-phase material.
4. Structure
Structure is a general term for bination of atom arrangement including the types amounts and distribution of all types of material as well as grain size, defect etc.
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Ⅲ. Classification of Alloy Phases
1. According to structure
Solid Solution
Compound
In Solid Solution, atoms of ponent share mon lattice in variable proportion.
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2. According to position of the alloy in phase diagram
Terminal .
Intermediate .
or secondary .
α
B
A
β
α+β
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