材料概论复习资料

1、二影响材料使用的因素二 Materials behavior二 AvailabilityZCost二 Synthesis and production method （材料的合成与生产方法）二 Processing techniques二 Environmental acceptabilityFactors on the properties of materials二组成材料的各元素的原子结构，二 Atomic structure二原子间的相互作用、相互结合，二 Nature of chemical bonds二原子或分子在空间的排列分布和运动规律，二 Atomic ordering二原子集

2、合体的形貌特征.二 MicrostnjctureProperties of Materials二 Mechanical properties:二 The behavior of materials deformed by a set of forces.二弹性 Elasticity二塑性 Plasticity二强度Strength二硬度Hardness二韧性Toughness二疲劳特性Fatigue behaviour二耐磨性 Abrasion resistanceClassification of materials: based on atomic stmctuies and the na

3、ture of bondsMetals and their alloysOrganic polymersCeramicsMechanical propenies : which reflect the behavior of materials deformed by a set of forcesPhysical properties : which describe the behavior of niatenals subjected to the action of tempeianire ,electnc or magnetic fields .01 light.Chemical p

4、roperties : which characterize the behavior of material in a reactive environment.PerformancesCompositionStructureTypes of materials1 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 t

5、o sudden and severe loads .2 ceiaimcs and glassesChenucal stable , sigmificantly higher melting point. brittleness3 polymers polymers are frequently lightweight Jowcost Jower strength Jower melting point and higher chemical reactivity4 composites it carries along the supenoi properties of each compo

6、nent, producing a product that is superior to either of the components separatelySolids exist in the nature m two principal forms : crystalline and amorphousAn elementary cell of crystal lattice is described二 Three sections a, b, and ct二 Three angles made by each two of these sections, a,八 and y .二晶

7、格常数lattice constant/ lattice spacing: b、c.crystal structure : body-centered cubic stmcture , face-centered cubic structure , hexagonal close-packed structurethe properties of crystals are different in various crystallographic directions ,which are associated with an ordered arrangement of atoms in s

8、pace.Advantages of Metals 二 Strong二 Soft: Cutting, Machining, Shaping二 Melting and casting二 Heat conductive二 Electric conductive二 Light-ReflectiveIron consist of slag and carbon .but steel consist of many element such as caibon .silicon .manganese .nickel and so onTlie types of cast iron ： white cas

9、t uon , gray cast iron , alloy cast uon . nodular or ductile cast uon . malleable cast ironAluminum二 Rust resistant二 High reflectivity二 Can be die cast二 Easily machined二 Good formabilitv .二 Nonmagiwtic二 Nontoxic二 One-third the stiffness of steelOik- third of the weight of steelGood thermal and elect

10、rical conductivityHigh strength-to-weight ratioCan be given a hard surface by anodizing and hard coatingMost alloys aie weldableCopper and its alloys : copper , brass and bronzeZ Magnesium二 The lightest of all structural metals二 Specific gravity: 1.75二 Magnesium weighs 1.5 times less thanan equal vo

11、lume of alununuin and 4 tunesless than zinc二 High strength, stiffiiess. dimensionalstability,二 High strength-to-weight ratio二 Alloys have二 Relatively high thermal and electricalconductivities;二 Good energy absorption characteristics;二 Nonmagnetic propertiesMechanical propertiesFor basic types of str

12、esses : tensile, compressive shear .torsion （拉力，压力，剪切力，扭转力）Strength : the strength of a metal is its ability to resist changing its shape or size when external forces are applied.Elasticity : the ability of a material to strain under load and then return to its original shape and size when unloaded.

13、Yield point : yielding or plastic flow occurs in materials when the elastic limit has been exceeded.Plasticity : nwtals undergo plastic flow whrn stressed at or beyond their clastic limits .Brittleness : a material that will not deform plastically is said to be brittle .Stiffness : stifTness is expr

14、essed by the modulus of elasticity.Ductility : the property that allows a metal to deform permanently when loaded in tension .As temperature decreases ,the strength .hardness .and the modulus of elasticity increase for almost all the metals Metals and nonmetals二 Ability to donate electrons and form

15、a positive ion二 Crystalline structure二 High thermal and electrical conductivity二 Ability to be deformed plastically二 Metallic luster （光泽）or reflectivityBody-centered cubic : columbium, barium, vanadium,（同. 想 划Face-centered cubic : calcium.aluminum.copper, lead .nickel gold Hexagonal close-packed : z

16、inc,titanium,magnesiumZ There are seveial ways to protect against conosion Corrosion can be prevented or lessened by二 Coatings,二 Design considerations.二 Enviromnental control.二 Alloying, among othersCeramic compounds:ZCan be defined as inorganic compounds made by heating clay or other mineral matter

17、 to a high temperature at which they partially melt and bond together.7Traditional ceramics are derived and processed from clay or nonclay minerals.Most advanced ceramics are produced from fine .relatively poor powers using new technologyThe property of ceramics二 Extreme hardness 二 Heat resistance 二

18、 Corrosion resistance 二 Low electrical and thermal conductivity 二 Low ductility （bnttleness）Pores affect the strength of ceramics in two ways：二they produce stress concentrations. Once the stress reaches a critical level, a crack will form and propagate.Z pores reduce the cross-sectional areas over w

19、hich a load can be applied and. consequently, lower the stress that these materials can support.Definition of glassGlass is an inorganic product of fusion which has cooled to a rigid condition without crystallization.Glass formationGlass formation occurs in materials of all chemical types : covalent

20、, ionic , molecular, metallic and hydrogen bonded materials. Glass have been made from element, simple chemical compounds, complex organic molecules , salt mixtures and alloys . there is no particularly advantageous way of grouping glass forming materials.Composition of oxide glass二 Main oxides in g

21、lass二 Glass formers: an oxide whichforms a glass easily （形成体）B2O3, SiO2, P2O5.二 Glass modifiers:（修改体）Li2O, Na2O. K2O, MgO. CaO .Z Intermediates:（中间体）TiO2. ZnO. PbO, AI2O3Two model of glass1 continuous random network model2 random close packing modelPhysical propertiesDensity : glass cooled at various rates from above the annealing point will differ in density with the more rapidly cooled glasses having a lower densityStrength : The measured mechanical strength of glass is much lo