材料概论复习资料1.doc

影响材料使用的因素

Materials behavior

Availability

Cost

Synthesis and production method

（材料的合成与生产方法）

Processing techniques

Environmental acceptability

Factors on the properties of m aterials

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组成材料的各元素的原子结构，

Atomic structure

原子间的相互作用、相互结合，

Nature of chemical bonds

原子或分子在空间的排列分布和运动规律，

Atomic ordering

原子集合体的形貌特征。

Microstructure

Properties of Materials

Mechanical properties:

The behavior of materials deformed by a set

of forces

?

弹性

El asticity

塑性

Plasticity

强度

Strength

硬度

Hardness

韧性

Toughness

疲劳牛寺性

Fatigue behaviour

而寸磨性

Abrasion resistance

Classification of materials: based on atomic structures and the nature of

bonds

Metals and their alloys

Organic polymers

Ceramics

Mechanical properties : which reflect the behavior of materials Reformed

by a set of forces

Physical properties : which describe the behavior of materials subjected to

the action of temperature ^electric or magnetic fields

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or light

?

Chemical properties : which characterize the behavior of material in a

reactive environment.

Performances

Structure

Types of materials

1

metal it is strong and can be readily formed into practical shapes .its

extensive , permanent ductility is an important asset in permitting small

amounts of yielding to sudden and severe loads

?

2

ceramics and glasses

Chemical stable , siginificantly higher melting point , brittleness

3

polymers

polymers are frequently lightweight

Jowcost Jower strength

」

ower melting point and

higher chemical reactivity

4

composites it carries along the superior properties of each component,

producing a product that is superior to either of the components separately

Solids exist in the nature in two principal forms : crystalline and

amorphous

An elementary cell of crystal lattice is described

Three sections a, b, and c,

Three angles made by

each two of these sections,

Q

, B , and

Y

?

晶格常数

lattice constant /

lattice spacing: a> b

、

c.

crystal structure : body-centered cubic structure , face-centered

cubic structure , hexagonal close-packed structure

the properties of crystals are different in various crystallographic

directions ,which are associated with an

ordered arrangement of atoms in space.

Advantages of Metals

Strong

Soft: Cutting, Machining, Shaping

Melting and casting

Heat conductive

Electric conductive

Light-Reflective

Iron consist of slag and carbon

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but steel consist of many element such as

carbon ^silicon ^manganese ,nickel and so on.

The types of cast iron

；

white cast iron , gray cast iron , alloy cast iron ,

nodular or ductile cast iron , malleable cast iron Alum inum

Rust resistant

High reflectivity

Can be die cast

Easily machined

Good formability

Nonmagnetic

Nontoxic

One- third the stiffness of steel

One third of the weight of steel